Packaging inserts with myoglobin blooming agents, packages and methods of packaging

ABSTRACT

Food packaging inserts comprising a myoglobin blooming agent that promote or preserve the desirable appearance of food products, food packages, and methods of food packing comprising the same, are provided.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/523,953 filed on Sep. 20, 2006 which is incorporated hereinby reference in its entirety. U.S. patent application Ser. No.11/523,953 is a continuation-in-part of International Patent ApplicationNo. PCT/US2005/011387, filed Apr. 4, 2005, which claims the benefit ofU.S. Provisional Application No. 60/559,350, filed Apr. 2, 2004, both ofwhich are incorporated herein by reference in their entirety. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 11/413,504, filed Apr. 28, 2006, entitled “Myoglobin BloomingAgent Containing Shrink Films”; Ser. No. 11/436,159, filed May 17, 2006,entitled “Packaging Articles, Films and Methods That Promote or Preservethe Desirable Color of Meat”; Ser. No. 11/451,968, filed Jun. 12, 2006,entitled “Myoglobin Blooming Agent, Films, Packages and Methods forPackaging” and Ser. No. 11/506,322, filed Aug. 18, 2006, entitled “WebsWith Synergists That Promote or Preserve the Desirable Color of Meat,”each of which is a continuation-in-part of International. PatentApplication No. PCT/US2005/011387, filed Apr. 4, 2005, which claims thebenefit of U.S. Provisional Application No. 60/559,350, filed Apr. 2,2004. These applications are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

Food packaging inserts comprising a myoglobin blooming agent, foodpackages, and methods of food packing comprising the same, are providedherein.

BACKGROUND

Meat color is an important quality characteristic of packaged meatproducts that affects their merchantability. Consumers often use coloras an indicator of meat quality and freshness. The color of meat isrelated to the amount and chemical state of myoglobin in the meat.Myoglobin is present in the muscle tissue of all animals and functionsto store and deliver oxygen by reversibly binding molecular oxygen,thereby creating an intracellular source of oxygen for the mitochondria.Pork and poultry typically contain lower amounts of myoglobin than beefand thus are lighter in color than beef.

Myoglobin includes an open binding site called heme that can bindcertain small molecules, such as molecular oxygen (O₂ or “oxygen”), orwater. Myoglobin, without a molecule bound to the heme site, is a purplecolored molecule called deoxymyoglobin. The presence and type of ligandbound at the myoglobin binding site can alter the color of themyoglobin. The color of the meat product will change based on the amountof myoglobin present and the amount and type(s) of ligand molecule(s)bound to the heme binding site. Molecular oxygen readily acts as aligand that binds to the heme group, permitting biological transport ofoxygen from the blood stream to the mitochondria within cells. Whenoxygen binds to the heme pocket, purple deoxymyoglobin becomesoxymyoglobin, characterized by a red color. When a water molecule bindsto the heme group, the myoglobin molecule turns brown and is referred toas metmyoglobin. The binding of carbon monoxide (CO) can cause a redcolor similar to that produced by oxygen binding. Nitric oxide (NO),when bond to the heme group, has been described as forming a stable pinkcolor in cured meat.

Historically, fresh meat products available to consumers have beensubstantially prepared and packaged for end-use at the site of finalsale. Product packaging that preserves a desirable color of fresh meatcan promote the merchantability and appeal of the meat product forconsumers. Existing meat packaging technology can inadequately preservefavorable meat color for various reasons. The conventional packagingformat used by the retail grocer for fresh meat is to stretch a thinplastic film around a foam tray that supports the product. The film ispermeable to oxygen so that the color of the meat quickly blooms to abright red. However, the shelf life for the bright red color is onlyabout three days. Thus, this packaging format is undesirable because thecolor often becomes unacceptable before it is sold even though the meatremains nutritious and healthy for consumption. As a result, a packagingformat that maintains the fresh meat color for a longer period of timehas long been sought for centralized packaging operations.Alternatively, meat has been packaged in oxygen barrier, vacuum bags,which are vacuum sealed and prevent oxygen contact with the meat untilthe package is opened. Vacuum sealed red meat products are nutritious,healthy and have a long shelf life, however they may result in anundesirable purple meat color in the package that does not bloom to adesirable red color until the meat is exposed to air. Consumeracceptance of meat having a purple color is less than that of meathaving a red color. To provide meat with the consumer preferred redcolor, meat has also been packaged in a modified atmosphere package(“MAP”), wherein the meat is maintained in a sealed pocket containing anatmosphere that is different than ambient air. For example, one suchcommercially acceptable MAP contains an atmosphere enriched with oxygen(up to 80% by volume) to better maintain a preferred red color. Anothercase ready MAP maintains meat in carbon dioxide, with very low oxygencontent until just before display when the meat is exposed to oxygen tocause blooming to the desired red color. Alternatively, the meat can becontacted with a MAP having an atmosphere containing a smallconcentration of carbon monoxide (CO) (e.g., 0.4% by volume) to maintaina preferred red meat color. However, while CO-containing MAP maymaintain a shelf life comparable to vacuum packaged meat, the red colorinduced by the presence of CO can be perceived as “unnaturally” brightred. In addition, the red color developed by CO tends to extend througha significant portion of the meat product, causing a permanent “pinking”of the interior of the meat which may remain even after the meat hasbeen fully cooked. The bright red CO-myoglobin complex is referred to ascarboxymyoglobin. The presence of carbon monoxide can also disfavorablyimpact sales of CO-containing MAP packages among consumers.

One concern with modified atmosphere packaging, is that surfaces of themeat product not exposed to the modified atmosphere do not maintain thepreferred color of fresh meat. For example, surfaces of the meat notexposed to the modified atmosphere may retain the deoxymyoglobin pigmentand its characteristic purple color. Thus, when the package is opened,the meat cut presents both red and purple colors, which is notattractive to the consumer. What is needed are packaging methods andproducts which maintain the preferred color of fresh meat over allsurfaces of the packaged meat cut, and which also provide consistentcolor after cooking.

Meat surfaces not exposed to the modified atmosphere include thosesurfaces covered by packaging inserts such as absorbent pads or punctureresistant patches. Absorbent pads such as soaker pads are routinely usedin packaged meat products to absorb unwanted liquids that can present anunsanitary environment and an unfavorable appearance. Puncture resistantpatches are used to inhibit sharp portions of the meat product, such asbone parts, from puncturing the packaging material which can compromisethe contents of the package, create an unsanitary environment, as wellas an unfavorable appearance. What is needed are packaging inserts whichmaintain the preferred color of fresh meat over surfaces of the packedmeat cut which they cover or protect.

SUMMARY

In a first embodiment, a packaging insert for meat product packaging isprovided comprising a first layer comprising a myoglobin blooming agent.The packaging insert is sized smaller than the meat product package towhich it is to be inserted and at least a portion of the insert is incontact with the meat product. The packaging insert may further comprisea second layer, and in some aspects, a third layer. The layers maycomprise a meat contact layer, and a polymeric material, a non-wovenmaterial, a paper material, an absorbent material, or a water-solubleresin. One or more layers may be liquid permeable or impermeable.

In a second embodiment, a packaged meat product is provided comprisingan uncooked meat product and a packaging insert. The packaging insertcomprises a first layer comprising a myoglobin blooming agent selectedfrom the group consisting of nitric oxide donating compounds, nitrogenheterocycles, and sulfur monoxide donating compounds. The packaginginsert is sized smaller than a meat product package to which it is to beinserted and at least a portion of the insert is in contact with themeat product. In some aspects, the packaged meat product furthercomprises a container comprising a polymeric web having an oxygenbarrier polymeric layer and a food contact layer, the food contact layerhas a food contact surface, at least a portion of which is in contactwith at least a portion of a surface of the uncooked meat product.

In a third embodiment, a method of packaging a meat product to promoteor preserve a desirable appearance of the meat product is provided. Themethod comprises supplying a container comprising a polymeric web havingan oxygen barrier layer; providing a myoglobin-containing fresh meatproduct having a water content of at least 5 weight %; and providing apackaging insert comprising a first layer comprising a myoglobinblooming agent selected from the group consisting of nitric oxidedonating compounds, nitrogen heterocycles, and sulfur monoxide donatingcompounds. The packaging insert is sized smaller than the container towhich it is to be inserted and at least a portion of the insert is incontact with the myoglobin-containing fresh meat product. In someaspects, the method further comprises removing oxygen from anenvironment surrounding the myoglobin-containing fresh meat product; andstoring the fresh meat product in a substantially oxygen freeenvironment for a time sufficient to allow the desirable color toappear.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 a shows an exemplary packaging insert of the present inventioncomprising a first layer disposed between second and third layers, wherethe first layer comprises an absorbent material.

FIG. 1 b shows a side view of the packaging insert of FIG. 1 a.

FIG. 2 shows a side view of a second exemplary packaging insert having afirst layer comprising a myoglobin blooming agent.

FIG. 3 a shows a third exemplary packaging insert of the presentinvention comprising first and second layers, wherein the second layercomprises an absorbent material.

FIG. 3 b shows a side view of the packaging insert of FIG. 3 a.

FIG. 4 shows a puncture resistant packaging insert of the presentinvention.

FIG. 5 shows a cross sectional schematic of a meat-containing tray witha barrier film overwrap.

FIG. 6 shows a top view of vacuum skin packaging film enclosed meat cut.

FIG. 7 shows a cross sectional schematic of a meat in a pre-formedcontainer.

FIG. 8 illustrates a puncture resistant packaging insert protecting thebone of a meat such as a ham.

FIG. 9 illustrates a puncture resistant packaging insert in a bag.

FIG. 10 shows a cross-sectional view of the bag of FIG. 9 taken alonglines 91-91.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Definitions

Myoglobin includes a non-protein portion called heme and a proteinportion called globin. The heme portion includes an iron atom in aplanar ring. The globin portion can provide a three-dimensionalstructure that surrounds the heme group and stabilizes the molecule. Theheme group provides an open binding site that can bind certain ligandshaving the proper shape and electron configuration to the iron atom.When a ligand enters and binds to the heme pocket, the electronconfiguration of the ligand affects light absorption characteristics ofthe heme group. Therefore, the presence or absence of a ligand such asoxygen in the heme pocket, and the ligand itself can result in visiblecolor changes of myoglobin.

When there is no ligand in the heme pocket, myoglobin is calleddeoxymyoglobin, which has a purple color (which is sometimescharacterized as purple, deep red, dark red, reddish blue or bluishred). Molecular oxygen, O₂ (“oxygen”), readily acts as a ligand thatbinds to the heme group, permitting biological transport of oxygen fromthe blood stream to the mitochondria within cells. When oxygen binds tothe heme pocket, purple deoxymyoglobin becomes oxymyoglobin,characterized by a red color. Upon dissociation of the oxygen ligandfrom oxymyoglobin, the iron atom is oxidized leaving the iron in theferric state. The oxidation of the iron atom renders the moleculeincapable of normal oxygen binding. As the chemical state of iron canchange from ferrous (Fe²⁺) to ferric (Fe³⁺), the three-dimensionalstructure of the globin part can change in a manner that allows watermolecules to bind to the heme pocket. Binding of a water molecule in theferric iron containing heme pocket affects light absorption of the hemepocket. The oxidized form of myoglobin with a water molecule in the hemegroup is referred to as metmyoglobin and its color is brown. Theoxidation of the iron atom is believed to result in a brown color. Hemeligands other than oxygen or water may also affect meat color. Forexample, the presence of carbon monoxide (CO) may cause fresh meat tohave a desirable bright red color similar to oxygen. Although it hasbeen suggested that nitric oxide (NO) can cause a dull red color (orstable pink color in the case of cured meat which also contains sodiumchloride), it has been discovered that in the absence of oxygen, NO mayproduce a desired bright red color similar to that caused by oxygen inuncooked meat, especially in fresh, raw, unprocessed or uncured meat. Ithas been discovered that the development of this desired bright redcolor may take many hours and typically may take from 1 to 5 days andthat initially, the meat color in a vacuum package having an oxygenbarrier may turn to an undesirable brown until the unexpectedtransformation to the desired red takes place.

Other variables that affect the stability of the globin portion alsoaffect the affinity of the heme group for oxygen and the tendency of thechemical state of the iron atom to become oxidized. Acidity and hightemperature, such as that associated with cooking, can denature theglobin part thus leading to instability of the heme group. In theabsence of stabilizing ligands, the oxidation of the heme iron isautomatic when the globin is denatured.

A “myoglobin blooming agent” refers to any agent (or precursor thereof)that binds to or interacts with any undenatured myoglobin-containingstructure (including but not limited to deoxymyoglobin, oxymyoglobin,metmyoglobin, carboxymyoglobin, and nitroxymyoglobin) present in a freshmeat product to produce or preserve a desired color, such as a red colorindicative of fresh meat. The myoglobin blooming agent may also interactor cause an interaction with hemoglobin present in a meat product so asto produce, maintain or enhance, i.e., “fix” a desired color. Thus, themyoglobin blooming agent is not a color additive, but it acts as a colorfixative. Examples of myoglobin blooming agents include gases such asoxygen and carbon monoxide.

“Deoxymyoglobin” refers to myoglobin in which no oxygen is present inthe heme pocket. The heme iron atom is in the reduced ferrous state. Itis theorized that a liquid water molecule is the ligand in the hemepocket. Deoxymyoglobin is associated with the unbloomed purple pigmentof fresh meat.

“Oxymyoglobin” refers to the oxygenated form of deoxymyoglobin where theheme ligand is an oxygen gas molecule. Oxymyoglobin is associated withthe bloomed red pigment of fresh meat

“Metmyoglobin” refers to an oxidized form of myoglobin in which the hemeiron is in the oxidized ferric state. Metmyoglobin can be formed whenoxygen leaves the heme pocket of oxymyoglobin and takes an electron withit leaving the heme iron atom in the oxidized ferric state. Metmyoglobincauses the characteristic oxidized brown pigment of fresh meat.

“Carboxymyoglobin” refers to the undenatured reduced form of thecarboxylated deoxymyoglobin pigment where the heme ligand is carbonmonoxide. The color of carboxymyoglin is red.

“Nitroxymyoglobin” is the undenatured reduced form of the nitrosylateddeoxymyoglobin pigment. The heme ligand is a nitrogen monoxide (NO)molecule. Nitrogen monoxide is also referred to as nitric oxide.Nitroxymyoglobin is also referred to as nitric oxide myoglobin,nitrosohaemachromagen, or nitrosomyoglobin among others.Nitroxymyoglobin has the same red color as oxymyoglobin andcarboxymyoglobin.

“Nitric oxide metmyoglobin” is the undenatured oxidized form ofdeoxymyoglobin when nitrite is present. It is used to describe the browncolor of meat that typically occurs after nitrite is added during thecuring process.

“Nitrosohemochrome” refers to the nitrosylated protoporphyrin (hemecomplex) that is detached from the globin protein moiety of themyoglobin molecule. Nitrosohemochrome affords the stable pink to marooncolor of cooked cured processed meat, wherein the heme iron is in thereduced state.

In fresh meat (postmortem muscle tissue), oxygen can continuallyassociate and disassociate from the heme complex of the undenaturedmyoglobin molecule. It is the relative abundance of three forms of theundenatured muscle pigment that determines the visual color of freshmeat. They include purple deoxymyoglobin (reduced myoglobin), redoxymyoglobin (oxygenated myoglobin); and brown metmyoglobin (oxidizedmyoglobin). The deoxymyoglobin form typically predominates immediatelyafter the animal is slaughtered. Thus, freshly cut meat can have apurple color. This purple color can persist for a long time if thepigment is not exposed to oxygen. Cutting or grinding exposes thepigment to oxygen in the atmosphere, and the purple color can quicklyconvert to either bright red (oxymyoglobin) or brown (metmyoglobin).Thus, although deoxymyoglobin is technically indicative of fresher meat,it is the red or “bloomed” meat color that consumers use as theirprimary criterion for perceiving freshness. It is believed withoutwishing to be bound by the belief, that the preferred red color of freshmeat occurs when at least 50% of the deoxymyoglobin molecules areoxygenated to the oxymyoglobin state. Changes in the relative percentageof each of these forms can continue to occur as fresh meat is exposed tooxygen for longer periods of time. The immediate conversion of thepurple color to the desirable bright red or undesirable brown can dependon the partial pressure of oxygen at the surface. The purple color isfavored at the very low oxygen level, and can dominate at oxygen levelsof 0-0.2% by volume. The brown color is favored when the oxygen level isonly slightly higher (0.2% to 5.0% by volume). Consumer discriminationtypically begins when the relative an amount of metmyoglobin is 20%. Adistinctly brown color is evident at 40% metmyoglobin, which typicallyrenders the meat unsaleable even though it remains nutritious andhealthy for consumption.

Certain biochemical reactions that occur in muscle tissue after deathcan also affect fresh meat color, such as the presence of activeglycolytic enzymes that convert oxygen to carbon dioxide. Reducingcoenzymes called metmyoglobin reductases present in meat convertmetmyoglobin back to deoxymyoglobin, and their activity is called “MRA”which is an abbreviation for metmyoglobin reducing activity. MRA can bedescribed as the ability of muscle to reduce metmyoglobin back to itsnatural deoxymyoglobin state. MRA is lost when the oxidizable substratesare depleted or when heat or acid denatures the enzymes. When theenzymes lose their activity or are denatured, the iron of the hemepigment automatically oxidizes to the metmyoglobin form, and the browncolor stabilizes and dominates. MRA persists for a period of time afterdeath depending on the amount of exposure of the meat tissue to oxygen.During this time, oxygen is continually consumed by the meat tissue. Theoxygen consumption rate is referred to as “OCR”. When meat that has ahigh OCR is exposed to oxygen, the oxygen tension is reduced so rapidlythat the metmyoglobin is favored below the viewing surface. If it isclose to the viewing surface, the perceived color of the meat isaffected. The MRA is important to minimize this layer of metmyoglobinthat forms between the bloomed surface and purple interior. As the MRAwears out, the brown metmyoglobin layer thickens and migrates toward thesurface, thus terminating display life. When the MRA is high, themetmyoglobin layer is thin and sometimes not visible to the naked eye.

MRA and OCR relate to determining the types of packaging best suited forretail sale in order to prolong the desirable appearance of meat as longas possible. Hermetically sealed packages with films that are a barrierto oxygen will cause a low oxygen tension on the meat surface. Thus,metmyoglobin formation occurs and the viewing surface changes to anundesirable brown color. However, if the OCR is high enough to keepahead of the oxygen that migrates across the packaging film, and the MRAis good enough to reduce metmyoglobin that forms on the surface, thennative deoxymyoglobin replaces metmyoglobin. After a period of time, theperceived color changes from brown to purple. Both of these colors areunacceptable to the consumer. For this reason, vacuum packaging byitself has historically been an unacceptable format for case ready freshmeat although it is used to ship subprimal and other large cuts of meatfrom the slaughterhouse to retail butchers for further processing andre-packaging. On the other hand, vacuum packaging is the format ofchoice for cooked and cured processed meats where the myoglobin pigmentis denatured by heat. Heat from cooking causes the globin portion of thenitrosylated myoglobin molecule to denature and separate from the hemeportion. It is the dissociated nitrosylated heme complex that givescured and processed meats their characteristic color. When oxygen iseliminated from a cured processed meat package, the product's color andflavor can deteriorate slower than when oxygen is present. In thepresent invention, it is advantageous to reduce or eliminate oxygen fromthe environment of the raw fresh meat in order to maximize thedevelopment of the preferred red color. A certain amount of oxygen maypenetrate the meat after slaughter and fabrication. This oxygen iseliminated by the OCR/MRA activities. Similarly, those activitiesfacilitate the dominance of the deoxymyoglobin form of the myoglobinmolecule. It is believed, but not wishing to be bound by the belief,that the OCR/MRA activities also facilitate the reduction of nitrite tonitric oxide when sodium nitrite is used as the myoglobin bloomingagent. In this case, the formation of deoxymyoglobin and nitric oxideallows for development of nitroxymyoglobin. Oxygen itself is a myoglobinblooming agent because it causes the formation of oxymyoglobin asdescribed earlier herein. However, oxygen interferes with the reactionsthat form deoxymyoglobin and nitric oxide. Therefore, it may interferewith the bloomed color development in the presence of nitrite. Thus, itis a preferred aspect of the present invention that an oxygen barrierlayer is selected and configured to protect the meat surface from theingress of atmospheric oxygen during the formation of the desiredbloomed meat color.

The term “superabsorbent” refers to a special group of polymers thathave the ability to absorb many times their own mass of liquid.Superabsorbents are configured to swell very rapidly in liquid, but notdissolve.

The term “meltblown fibers” means fine fibers of unoriented polymer.Meltblown fibers are microfibers which may be continuous ordiscontinuous, and are generally smaller than 10 microns in averagediameter. A process for making meltblow fibers is described in U.S. Pat.No. 3,849,241.

In discussing plastic packaging inserts or webs, various polymeracronyms are used herein and they are listed below. Also, in referringto blends of polymers, a colon (:) will be used to indicate that thecomponents to the left and right of the colon are blended. In referringto web structures, a slash “/” will be used to indicate that componentsto the left and right of the slash are in different layers and therelative position of components in layers may be so indicated by use ofthe slash to indicate web layer boundaries. Acronyms commonly employedherein include:

-   -   EAA—Copolymer of ethylene with acrylic acid    -   EAO—Copolymers of ethylene with at least one α-olefin    -   EBA—Copolymer of ethylene with butyl acrylate    -   EEA—Copolymer of ethylene with ethyl acrylate    -   EMA—Copolymer of ethylene with methyl acrylate    -   EMAA—Copolymer of ethylene with methacrylic acid    -   EVA—Copolymer of ethylene with vinyl acetate    -   EVOH—A saponified or hydrolyzed copolymer of ethylene and vinyl        acetate    -   PB—Polybutylene-1 (a butylene homopolymer and/or copolymer of a        major portion of butylene-1 with one or more α-olefins; also        known as butene-1)    -   PE—Polyethylene (an ethylene homopolymer and/or copolymer of a        major portion of ethylene with one or more α-olefins)    -   PP—Polypropylene homopolymer or copolymer    -   PET—Poly(ethylene terephthalate)    -   PETG—glycol-modified polyethylene terephthalate    -   PLA—Polylactic acid; also known as polylactide    -   PVDC—Polyvinylidene chloride (also includes copolymers of        vinylidene chloride, especially with vinyl chloride and/or        methyl acrylate (MA)), also referred to as saran.

A “core layer,” as used herein, refers to a layer positioned between andin contact with at least two other layers.

An “outer layer,” as used herein is a relative term and needs not be asurface layer.

The term “exterior layer” refers to a layer comprising the outermostsurface of a web or product. For example, an exterior layer can form theexterior surface of a package that contacts the exterior layer ofanother package during overlapping heat sealing of two packages.

The term “interior layer” refers to a layer comprising the innermostsurface of a web or product. For example, an interior layer forms theinterior surface of an enclosed package. The interior layer can be thefood-contact layer and/or the sealant layer.

As used herein, the term “barrier,” and the phrase “barrier layer,” asapplied to web and/or web layers, are used with reference to the abilityof a web or web layer to serve as a barrier to one or more gases ormoisture.

As used herein, the term “cellulose” is used to include any natural orsynthetic material comprising paper fibers, wood fibers, wood pulp orpowder and the like, preferably cellulosic fibers such as rayon,lyocell, cellulose acetate, cellulose carbamate, and deacetylatedcellulose acetate, and regenerated cellulose, e.g., cellophane.

The term “nonwoven” as used herein refers to nonwoven papers, fabrics,or textiles and includes spunbonded webs, dry lay webs, and wet laywebs. Nonwovens are made from natural or synthetic fibers bound togetherin a web. “Nonwoven web” refers to a web that has a structure ofindividual fibers or threads which are interlaid, but not in anyregular, repeating manner. Nonwoven webs may be formed by a variety ofprocesses, such as for example, meltblowing processes, spunbondingprocesses and bonded carded web processes.

The term “nanocomposite” shall mean a mixture that includes a polymer,or copolymer having dispersed therein a plurality of individualplatelets which may be obtained from exfoliated modified clay and havingoxygen barrier properties.

The term “adhesive layer,” or “tie layer,” refers to a layer or materialplaced on one or more layers to promote the adhesion of that layer toanother surface. Preferably, adhesive layers are positioned between twolayers of a multilayer film to maintain the two layers in positionrelative to each other and prevent undesirable delamination. Unlessotherwise indicated, an adhesive layer can have any suitable compositionthat provides a desired level of adhesion with the one or more surfacesin contact with the adhesive layer material. Optionally, an adhesivelayer placed between a first layer and a second layer in a multilayerweb may comprise components of both the first layer and the second layerto promote simultaneous adhesion of the adhesive layer to both the firstlayer and the second layer to opposite sides of the adhesive layer. Tieor adhesive layers may be incorporated into the article by any of thewell known processes for making multilayer structures such ascoextrusion, adhesive lamination and the like.

As used herein, the phrases “seal layer,” “sealing layer,” “heat seallayer,” and “sealant layer,” refer to an outer web layer, or layers,involved in the sealing of the web: to itself; to another film layer ofthe same film or another web; and/or to another article which is not aweb, e.g., a tray. In general, the sealant layer is a surface layer,i.e., an exterior or an interior layer of any suitable thickness, thatprovides for the sealing of the web to itself or another layer. Withrespect to packages having only fin-type seals, as opposed to lap-typeseals, the phrase “sealant layer” generally refers to the interiorsurface film web of a package. The inside layer frequently can alsoserve as a food contact layer in the packaging of foods.

“Food contact layer,” “food contact portion” or “food contact surface”refers to the portion of a packaging material that contacts a packagedmeat product. Preferably, the food packaging film includes a foodcontact layer. At least one of a food contact layer or non-food contactlayer comprises a myoglobin blooming agent in an amount effective topromote or preserve the desirable appearance or color of the meatproduct.

As used herein, the term “lamination”, and the phrase “laminated film”,refer to the process, and resulting product, made by bonding togethertwo or more webs or other materials. Lamination can be accomplished byjoining webs together with adhesives, joining with heat and pressure,and even spread coating and extrusion coating. The term laminate is alsoinclusive of coextruded multilayer webs comprising one or more tielayers.

“Polyolefin” is used herein broadly to include polymers such aspolyethylene, ethylene-alpha olefin copolymers (EAO), polypropylene,polybutene, and ethylene copolymers having a majority amount by weightof ethylene polymerized with a lesser amount of a comonomer such asvinyl acetate, and other polymeric resins falling in the “olefin” familyclassification. Polyolefins may be made by a variety of processes wellknown in the art including batch and continuous processes using single,staged or sequential reactors, slurry, solution and fluidized bedprocesses and one or more catalysts including for example, heterogeneousand homogeneous systems and Ziegler, Phillips, metallocene, single siteand constrained geometry catalysts to produce polymers having differentcombinations of properties. Such polymers may be highly branched orsubstantially linear and the branching, dispersity and average molecularweight may vary depending upon the parameters and processes chosen fortheir manufacture in accordance with the teachings of the polymer arts.

“Polyethylene” is the name for a polymer whose basic structure ischaracterized by the chain —(CH₂—CH₂—)_(n). Polyethylene homopolymer isgenerally described as being a solid which has a partially amorphousphase and partially crystalline phase with a density of between 0.860 to0.970 g/cm³. The relative crystallinity of polyethylene is known toaffect its physical properties. The amorphous phase imparts flexibilityand high impact strength while the crystalline phase imparts a highsoftening temperature and rigidity.

Unsubstituted polyethylene is generally referred to as high densityhomopolymer and has a crystallinity of 70 to 90 percent with a densitybetween about 0.96 to 0.97 g/cm³. Most commercially utilizedpolyethylenes are not unsubstituted homopolymer but instead have C₂-C₈alkyl groups attached to the basic chain. These substitutedpolyethylenes are also known as branched chain polyethylenes. Also,commercially available polyethylenes frequently include othersubstituent groups produced by copolymerization. Branching with alkylgroups generally reduces crystallinity, density and melting point. Thedensity of polyethylene is recognized as being closely connected to thecrystallinity. The physical properties of commercially availablepolyethylenes are also affected by average molecular weight andmolecular weight distribution, branching length and type ofsubstituents.

People skilled in the art generally refer to several broad categories ofpolymers and copolymers as “polyethylene.” Placement of a particularpolymer into one of these categories of “polyethylene” is frequentlybased upon the density of the “polyethylene” and often by additionalreference to the process by which it was made since the process oftendetermines the degree of branching, crystallinity and density. Ingeneral, the nomenclature used is nonspecific to a compound but refersinstead to a range of compositions. This range often includes bothhomopolymers and copolymers.

For example, “high density” polyethylene (HDPE) is ordinarily used inthe art to refer to both (a) homopolymers of densities between about0.960 to 0.970 g/cm³ and (b) copolymers of ethylene and an alpha-olefin(usually 1-butene or 1-hexene) which have densities between 0.940 and0.958 g/cm³. HDPE includes polymers made with Ziegler or Phillips typecatalysts and is also said to include high molecular weight“polyethylenes.” In contrast to HDPE, whose polymer chain has somebranching, are “ultra high molecular weight polyethylenes” which areessentially unbranched specialty polymers having a much higher molecularweight than the high molecular weight HDPE.

Hereinafter, the term “polyethylene” will be used (unless indicatedotherwise) to refer to ethylene homopolymers as well as copolymers ofethylene with alpha-olefins and the term will be used without regard tothe presence or absence of substituent branch groups.

Another broad grouping of polyethylene is “high pressure, low densitypolyethylene” (LDPE). LDPE is used to denominate branched homopolymershaving densities between 0.915 and 0.930 g/cm³. LDPEs typically containlong branches off the main chain (often termed “backbone”) with alkylsubstituents of 2 to 8 carbon atoms or more.

Linear Low Density Polyethylenes (LLDPEs) are copolymers of ethylenewith alpha-olefins having densities from 0.915 to 0.940 g/cm³. Thealpha-olefin utilized is usually 1-butene, 1-hexene, or 1-octene andZiegler-type catalysts are usually employed (although Phillips catalystsare also used to produce LLDPE having densities at the higher end of therange, and metallocene and other types of catalysts are also employed toproduce other well known variations of LLDPEs).

Ethylene α-olefin copolymers (EAOs) are copolymers having an ethylene asa major component copolymerized with one or more alpha olefins such asoctene-1, hexene-1, or butene-1 as a minor component. EAOs includepolymers known as LLDPE, VLDPE, ULDPE, and plastomers and may be madeusing a variety of processes and catalysts including metallocene,single-site and constrained geometry catalysts as well as Ziegler-Nattyand Phillips catalysts.

Very Low Density Polyethylenes (VLDPEs) which are also called “Ultra LowDensity Polyethylenes” (ULDPEs) comprise copolymers of ethylene withalpha-olefins, usually 1-butene, 1-hexene or 1-octene and are recognizedby those skilled in the art as having a high degree of linearity ofstructure with short branching rather than the long side branchescharacteristic of LDPE. However, VLDPEs have lower densities thanLLDPEs. The densities of VLDPEs are recognized by those skilled in theart to range between 0.860 and 0.915 g/cm³. A process for making VLDPEsis described in European Patent Document publication number 120,503whose text and drawing are hereby incorporated by reference into thepresent document. Sometimes VLDPEs having a density less than 0.900g/cm³ are referred to as “plastomers”.

Polyethylenes may be used alone, in blends and/or with copolymers inboth monolayer and multilayer webs for packaging applications for suchfood products as poultry, fresh red meat and processed meat.

As used herein, the term “modified” refers to a chemical derivative,e.g., one having any form of anhydride functionality, such as anhydrideof maleic acid, crotonic acid, citraconic acid, itaconic acid, fumaricacid, etc., whether grafted onto a polymer, copolymerized with apolymer, or otherwise functionally associated with one or more polymers,and is also inclusive of derivatives of such functionalities, such asacids, esters, and metal salts derived therefrom. Another example of acommon modification is acrylate modified polyolefin.

As used herein, terms identifying polymers, such as, e.g., “polyimide”or “polypropylene,” are inclusive of not only polymers comprisingrepeating units derived from monomers known to polymerize to form apolymer of the named type, but are also inclusive of comonomers, as wellas both unmodified and modified polymers made by, e.g., derivitizationof a polymer after its polymerization to add functional groups ormoieties along the polymeric chain. Furthermore, terms identifyingpolymers are also inclusive of “blends” of such polymers. Thus, theterms “polyamide polymer” and “nylon polymer” may refer to apolyamide-containing homopolymer, a polyamide-containing copolymer ormixtures thereof.

The term “polyamide” means a high molecular weight polymer having amidelinkages (—CONH—)_(n) which occur along the molecular chain, andincludes “nylon” resins, which are well known polymers having amultitude of uses including utility as packaging inserts, webs, films,sheets, bags, and casings. See, e.g., Modern Plastics Encyclopedia, 88Vol. 64, No. 10A, pp 34-37 and 554-555 (McGraw-Hill, Inc., 1987) whichis hereby incorporated by reference. Polyamides are preferably selectedfrom nylon compounds approved for use in producing articles intended foruse in processing, handling, and packaging food.

The term “nylon” as used herein refers more specifically to syntheticpolyamides, either aliphatic or aromatic, either in crystalline,semi-crystalline, or amorphous form characterized by the presence of theamide group —CONH. It is intended to refer to both polyamides andco-polyamides.

Thus the terms “polyamide” or “nylon” encompass both polymers comprisingrepeating units derived from monomers, such as caprolactam, whichpolymerize to form a polyamide, as well as copolymers derived from thecopolymerization of caprolactam with a comonomer which when polymerizedalone does not result in the formation of a polyamide. Preferably,polymers are selected from compositions approved as safe for producingarticles intended for use in processing, handling and packaging of food,such as nylon resins approved by the U.S. Food and Drug Administrationprovided at 21 CFR §177.1500 (“Nylon resins”), which is incorporatedherein by reference. Examples of these nylon polymeric resins for use infood packaging and processing include: nylon 6,6, nylon 6,10, nylon6,6/6,10, nylon 6/6,6, nylon 11, nylon 6, nylon 6,6T, nylon 6,12, nylon12, nylon 6/12, nylon 6/6,9, nylon 4,6, nylon 6-3-T, nylon MXD-6, nylonMXDI, nylon 12T and nylon 6I/6T disclosed at 21 CFR §177.1500. Examplesof such polyamides include nylon homopolymers and copolymers such asthose selected form the group consisting of nylon 4,6(poly(tetramethylene adipamide)), nylon 6 (polycaprolactam), nylon 6,6(poly(hexamethylene adipamide)), nylon 6,9 (poly(hexamethylenenonanediamide)), nylon 6,10 (poly(hexamethylene sebacamide)), nylon 6,12(poly(hexamethylene dodecanediamide)), nylon 6/12(poly(caprolactam-co-dodecanediamide)), nylon 6,6/6 (poly(hexamethyleneadipamide-co-caprolactam)), nylon 6,6/6,10 (e.g., manufactured by thecondensation of mixtures of nylon 6,6 salts and nylon 6,10 salts), nylon6/6,9 resins (e.g., manufactured by the condensation ofepsilon-caprolactam, hexamethylenediamine and azelaic acid), nylon 11(polyundecanolactam), nylon 12 (polylauryllactam) and copolymers ormixtures thereof.

In use of the term “amorphous nylon copolymer,” the term “amorphous” asused herein denotes an absence of a regular three-dimensionalarrangement of molecules or subunits of molecules extending overdistances which are large relative to atomic dimensions. However,regularity of structure may exist on a local scale. See, “AmorphousPolymers,” Encyclopedia of Polymer Science and Engineering, 2nd Ed., pp.789-842 (J. Wiley & Sons, Inc. 1985). In particular, the term “amorphousnylon copolymer” refers to a material recognized by one skilled in theart of differential scanning calorimetry (DSC) as having no measurablemelting point or no heat of fusion (less than 0.5 cal/g) as measured byDSC using ASTM 3417-83. The amorphous nylon copolymer may bemanufactured by the condensation of hexamethylenediamine, terephthalicacid, and isophthalic acid according to known processes. Amorphousnylons also include those amorphous nylons prepared from condensationpolymerization reactions of diamines with dicarboxylic acids. Forexample, an aliphatic diamine is combined with an aromatic dicarboxylicacid, or an aromatic diamine is combined with an aliphatic dicarboxylicacid to give suitable amorphous nylons.

As used herein, “EVOH” refers to ethylene vinyl alcohol copolymer. EVOHis otherwise known as saponified or hydrolyzed ethylene vinyl acetatecopolymer, and refers to a vinyl alcohol copolymer having an ethylenecomonomer. EVOH is prepared by the hydrolysis (or saponification) of anethylene-vinyl acetate copolymer. The degree of hydrolysis is preferablyfrom about 50 to 100 mole percent, more preferably, from about 85 to 100mole percent, and most preferably at least 97%. It is well known that tobe a highly effective oxygen barrier, the hydrolysis-saponification mustbe nearly complete, i.e., to the extent of at least 97%. EVOH iscommercially available in resin form with various percentages ofethylene and there is a direct relationship between ethylene content andmelting point. For example, EVOH having a melting point of about 175° C.or lower is characteristic of EVOH materials having an ethylene contentof about 38 mole % or higher. EVOH having an ethylene content of 38 mole% has a melting point of about 175° C. With increasing ethylene contentthe melting point is lowered. A melting point of about 158° C.corresponds to an ethylene content of 48 mole %. EVOH copolymers havinglower or higher ethylene contents may also be employed. It is expectedthat processability and orientation would be facilitated at highercontents; however, gas permeabilities, particularly with respect tooxygen, may become undesirably high for certain packaging applicationswhich are sensitive to microbial growth in the presence of oxygen.Conversely, lower contents may have lower gas permeabilities, butprocessability and orientation may be more difficult.

As used herein, the term “polyester” refers to synthetic homopolymersand copolymers having ester linkages between monomer units which may beformed by condensation polymerization methods. Polymers of this type arepreferably aromatic polyesters and more preferably, homopolymers andcopolymers of polyethylene terephthalate, polyethylene isophthalate,polybutylene terephthalate, polyethylene naphthalate and blends thereof.Suitable aromatic polyesters may have an intrinsic viscosity between0.60 to 1.0, preferably between 0.60 to 0.80.

As used herein, the term “ionomer” refers to an ionic copolymer formedfrom an olefin and an ethylenically unsaturated monocarboxylic acidhaving the carboxylic acid moieties partially neutralized by a metalion. Suitable metal ions may include, but are not limited to, sodium,potassium, lithium, cesium, nickel, and zinc. Suitable carboxylic acidcomonomers may include, but are not limited to, ethylene/methacrylicacid, succinic acid, itaconic acid, vinyl acetate/methacrylic acid,methyl/methacrylate/methacrylic acid, styrene/methacrylic acid andcombinations thereof. Useful ionomer resins may include an olefiniccontent of at least 50% (mol) based upon the copolymer and a carboxylicacid content of between 5-25% (mol) based upon the copolymer. Usefulionomers are also described in U.S. Pat. No. 3,355,319 to Rees, which isincorporated herein by reference in its entirety.

Myoglobin Blooming Agents

A “myoglobin blooming agent” refers to any agent (or precursor thereof)that binds to or interacts with any undenatured myoglobin-containingstructure (including but not limited to deoxymyoglobin, oxymyoglobin,metmyoglobin, carboxymyoglobin, and nitric oxide myoglobin) present in afresh meat product to produce or preserve a desired color, such as a redcolor indicative of fresh meat. The myoglobin blooming agent may alsointeract or cause an interaction with hemoglobin present in a meatproduct so as to produce, maintain or enhance, i.e., “fix” a desiredcolor. Thus, the myoglobin blooming agent is not a color additive, butit acts as a color fixative.

In one preferred embodiment, the myoglobin blooming agent is a “nitricoxide donating compound” (“NO donor”) that provides a nitric oxide (NO)molecule that binds to the myoglobin present in a meat product so as tomaintain or promote a reddening or blooming or other favorablecoloration of the meat product. A nitric oxide donating compoundreleases nitric oxide or is a precursor, e.g., nitrate which acts as anintermediate leading to the formation of nitric oxide which binds to amyoglobin molecule in a meat product. Examples of nitric oxide donatingcompounds include nitrosodisulfonates including for example, Fremy'ssalt [NO(SO₃Na)₂ or NO(SO₃K)₂]; inorganic nitrates (MNO₃) where asuitable counter ion (M⁺) include alkali metals (e.g., sodium,potassium), alkaline earth metals (e.g., calcium), transition metals,protonated primary, secondary, or tertiary amines, or quaternaryamities, or ammonium, and including for example, saltpeter; andinorganic nitrites (MNO₂) where suitable counter ions (M⁺) includealkali metals (e.g., sodium, potassium), alkaline earth metals (e.g.,calcium), transition metals, protonated primary, secondary, or tertiaryamines, or quaternary amines, or ammonium.

Other suitable nitric oxide donating compounds that may act as myoglobinblooming agents are disclosed in U.S. Pat. No. 6,706,274 to Herrmann etal. (filed Jan. 18, 2001); U.S. Pat. No. 5,994,444 to Trescony et al.(filed Oct. 16, 1997), and U.S. Pat. No. 6,939,569 to Green et al.(filed Jun. 18, 1999), as well as published U.S. Patent Application No.US2005/0106380 by Gray et al. (filed Nov. 13, 2003), all of which arehereby incorporated by reference herein. Optionally, the myoglobinblooming agents can contain materials that promote the conversion ofother materials to NO, such as nitrate reductase or nitrosothiolreductase catalytic agents, including the materials described in WIPOPublication No. WO 02/056904by Meyerhoff et al. (filed Jan. 16, 2002),which is incorporated herein by reference.

Other examples of nitric oxide donating compounds include organicnitroso compounds (containing a —NO functional group attached to carbon)including 3-ethyl-3-nitroso-2,4-pentanedione: organic nitro compounds(containing a —NO₂ functional group attached to carbon) includingnitroglycerine and 6-nitrobenzo[α]pyrene; organic nitrates (—O—NO₂)including ethyl nitrate, glyceryl mono, di or trinitrate,pentaerythritol tetranitrate, erythrityle tetranitrate, isosorbide monoor dinitrate, and trolnitrate.

Other examples of nitric oxide donating compounds include O-nitrosylatedcompounds (—O—NO) including alkyl nitrites such as butyl nitrite, amylnitrite, dodecyl nitrite and dicyclohexylamine nitrite; S-nitrosylatedcompounds (—S—NO) also known as nitrosothiols includingS-nitrosothioglycerol, S-nitroso-penicillamine, S-nitrosoglutathione,glutathione, S-nitroylated derivatives of captopril,S-nitrosylated-proteins, S-nitrosylated-peptides,S-nitrosylated-oligosaccharides and S-nitrosylated-polysaccharides; andN-nitrosylated compounds (—N—NO) including N-nitrosamines;N-hydroxy-N-nitrosoamines; and N-nitrosimines.

Additional examples of nitric oxide donating compounds include nonoatecompounds which include the functional group —N(O)—NO (also referred toin the art as N-oxo-N-nitroso compounds, N-hydroxy-N′-diazenium oxides,diazeniumdiolates and NONOates) including3,3,4,4-tetramethyl-1,2-diazetine 1,2-dioxide.

Further examples of nitric oxide donating compounds include transitionmetal/nitroso complexes including sodium nitroprusside, dinitrosyl ironthiol complexes, iron-sulfur cluster nitrosyls, ruthenium nitrosyls,nitroso/heme/transition metal complexes, and nitroso ferrousprotoporphyrin complexes; furoxans including 1,2,5-oxadiazole N-oxide;benzofuroxans, oxatriazole-5-imines including3-aryl-1,2,3,4-oxatriazole-5-imine; sydnonimines including molsidomine;oximes including cyclohexanone oxime; hydroxylamines,N-hydroxyguanidines, and hydroxyureas.

Nitric oxide donating compounds may donate one molecule of nitric oxideor multiple nitric oxide molecules. In some aspects the nitric oxidedonating compound may be a polymeric material which contains severalnitric oxide donating sites, and can thereby release multiple moleculesof nitric oxide. Preferably, the nitric oxide is released from thepolymeric chain. For example, U.S. Pat. No. 5,525,357, which is herebyincorporated by reference herein, describes a polymer with a nitricoxide-releasing functional group bound to the polymer. U.S. Pat. No.5,770,645, which is hereby incorporated by reference herein, describes apolymer in which NO_(x) is covalently bound to a polymer by a linkinggroup. U.S. Pat. No. 6,087,479, which is hereby incorporated byreference herein, describes synthetically derived polymeric materialswhich are derivatized to include nitric oxide adducts. It is to beunderstood that polymeric materials which contain a nitric oxidedonating compound or nitric oxide donating functional group chemicallybound to the polymer chain are within the scope of the presentinvention.

In one embodiment, the nitric oxide donating compound is other thansodium nitrate or sodium nitrite.

In one embodiment, the nitric oxide donating compound is other than aninorganic nitrate or inorganic nitrite.

In another embodiment, the nitric oxide donating compound is aninorganic nitrate or inorganic nitrite other than sodium nitrate,potassium nitrate, sodium nitrite and potassium nitrate.

In one embodiment, the nitric oxide donating compound is other than anitrosodisulfonate.

Other myoglobin blooming agents within the scope of the presentinvention include inorganic cyanides (MCN) where suitable counter ions(M⁺) include alkali metals (e.g., sodium, potassium), alkaline earthmetals (e.g., calcium), transition metals, protonated primary,secondary, or tertiary amines, or quaternary amines, or ammonium;inorganic fluorides (MF) where suitable counter ion (M⁺) include alkalimetals (e.g., sodium, potassium), alkaline earth metals (e.g., calcium),transition metals, protonated primary, secondary, or tertiary amines, orquaternary amines, or ammonium; isothiocyanates including mustard oil;bacterial cultures that fix nitrogen to provide a source of nitrogenoxide including xanthine oxidase, nitrate reductases, nitritereductases; betanine; erythrocine; and cochineal extracts.

Other myoglobin blooming agents include nitrogen heterocycles andderivatives. Examples of suitable nitrogen heterocycles includepyridines, pyrimidines (for example dipyridamole), pyrazines, triazines,purines (for example nicotinamide), nicotinates, niacin (also known asnicotinic acid), isoquinolines, imidazoles and derivatives and saltsthereof. It is to be understood that these nitrogen heterocycles may besubstituted or unsubstituted. For pyridines and isoquinolines,3-carbonyl substituted compounds are preferred. Preferably, the nitrogenheterocycle is a pyridine, pyrimidine or imidazole. More preferably, thenitrogen heterocycle is an alkali or alkaline earth metal salt or esterof nicotinic acid which may include such esters as methyl nicotinate,ethyl nicotinate, propyl nicotinate, butyl nicotinate, pentylnicotinate, hexyl nicotinate, methyl isonicotinate, isopropylisonicotinate, and isopentyl isonicotinate. More preferably the nitrogenheterocycle is an alkali or alkaline earth metal salt or ester ofnicotinamide. In another aspect, the nitrogen heterocycle is pyridine,pyrimidine, histidine, N-acetyl histidine, 3-butyroylpyridine,3-valeroylpyridine, 3-caproylpyridine, 3-heptoylpyridine,3-capryloylpyridine, 3-formylpyiridine, nicotinamide,N-ethylnicotinamide, N,N-diethylnicotinamide, isonicotinic acidhydrazide, 3-hydroxypyridine, 3-ethyl pyridine, 4-vinyl pyridine,4-bromo-isoquinoline, 5-hydroxyisoquinoline, or 3-cyanopyridine.

Myoglobin blooming agents also include any compound which acts as aligand for myoglobin and leads to the formation of the desirable color,or any compound which acts as a substrate leading to the formation ofsuch a ligand. For example, the myoglobin blooming agent can be a carbonmonoxide donating compound. Carbon monoxide is known to complex with theheme pocket of myoglobin to form a desirable appearance in meat. Acarbon monoxide donating compound is any compound that releases carbonmonoxide or acts as a substrate leading to the formation of carbonmonoxide. Alternatively, the blooming agent can be a sulfur monoxide(SO) donating compound, a nitrous oxide (N₂O) donating compound, anammonia (NH₃) donating compound or a hydrogen sulfide donating compound.Such compounds donate the specified ligand or act as a substrate leadingto the formation of the specified ligand. Compounds includeligand/heme/transition metal complexes, and ligand ferrousprotoporphyrin complexes, including for example, carbonmonoxide/heme/transition metal complexes, and carbon monoxide ferrousprotoporphyrin complexes. Carbon monoxide donating compounds, sulfurmonoxide donating compounds, nitrous oxide donating compounds andhydrogen sulfide donating compounds include polymeric materials with theappropriate donating functional group chemically bound to the polymerchain.

The myoglobin blooming agent is preferably present in a desiredconcentration in contact with a meat product. The packaging insertpreferably contains a blooming agent in a concentration high enough toproduce or preserve a desirable appearance in a meat product. It will beappreciated by those skilled in the art that a myoglobin blooming agentmay be present on or within the packaging insert and on or within apackaging web used to form a package for fresh meat. Preferably, theblooming agent is present in a concentration sufficient to convert atleast 50% of the myoglobin molecules on a contacting meat surface to adesired ligand binding state. The concentration of blooming agent ispreferably selected to bind ligands producing desirable appearance orcolor of the meat to the myoglobin molecules in the outermost ¼-inch orless of the meat product. For example, a nitric oxide donating myoglobinblooming agent is desirably present in a concentration sufficient toconvert at least 50% of the myoglobin molecules on the contacting meatsurface to nitric oxide myoglobin.

When the blooming agent is niacin, the concentration of niacin chosen isgreater than the concentration of niacin naturally found in meat.According to Richardson et al., (1980, Composition of foods. Sausage andluncheon meats (Raw, Processed, Prepared) Handbook No. 8-7, USDA,Science and Education Administration, Washington, D.C.), niacinnaturally occurs in poultry and red meat at about 0.05-0.09 mg/g. In thepresent invention, when niacin is employed as the blooming agent andincorporated in the meat product, it is typically used in amountsgreater than 0.1 mg/g of meat.

The myoglobin blooming agent may be coated on the exterior surface ofthe packaging insert by spraying or dusting or other application meansor the blooming agent may be incorporated within one or more layers usedto form the insert.

Other additives known to one skilled in the art can be added in additionto the blooming agent. These additives can be added directly to the foodproduct or to the packaging insert, either incorporated within or coatedor dusted on the surface. Examples of other additives include monosodiumglutamate, salt, cereal, soybean flour, soy protein concentrate,lactose, corn syrup solids, antimycotics (which suppress the growth ofyeasts and molds), antibiotics, sugar, glycerol, lactic acid, ascorbicacid, erythorbic acid, α-tocopherol, phosphates, rosemary extract andsodium benzoate.

Myoglobin blooming agents and solutions or dispersions thereof may becolorless, or, such as sodium nitrate, may have an intrinsic pale yellowcolor (i.e., may not be totally colorless), but this color does nottypically have sufficient intensity itself to act as a significantcolorant or color additive. However, this does not preclude either theuse of colored myoglobin blooming agents which impart an intrinsic coloror the combination of a myoglobin blooming agent in combination with oneor more natural and/or artificial colorants, pigments, dyes and/orflavorants such as annatto, bixin, norbixin, beet powder, caramel,carmine, cochineal, turmeric, paprika, liquid smoke, erythrosine,betanine, one or more FD&C colorants, etc.

The myoglobin blooming agent is believed to cause an interaction withmyoglobin in meat products, thereby maintaining, promoting or enhancinga desirable meat color. Myoglobin includes a non-protein portion calledheme and a protein portion called globin. The heme portion includes aniron atom in a planar ring. The globin portion can provide athree-dimensional structure that surrounds the heme group and stabilizesthe molecule. The heme group provides an open binding site that can bindcertain ligands having the proper shape and electron configuration tothe iron atom. When a ligand enters and binds to the heme pocket, theelectron configuration of the ligand affects light absorptioncharacteristics of the heme group. Therefore, the presence or absence ofa ligand such as oxygen in the heme pocket, and the ligand itself canresult in visible color changes of myoglobin.

When there is no ligand in the heme pocket, myoglobin is calleddeoxymyoglobin, which has a purple color (which is sometimescharacterized as purple, deep red, dark red, reddish blue or bluishred). Molecular oxygen, O₂ (“oxygen”) readily acts as a ligand thatbinds to the heme group, permitting biological transport of oxygen fromthe blood stream to the mitochondria within cells. When oxygen binds tothe heme pocket, purple deoxymyoglobin becomes oxymyoglobin,characterized by a red color. Upon dissociation of the oxygen ligandfrom oxymyoglobin, the iron atom is oxidized leaving the iron in theferric state. The oxidation of the iron atom renders the moleculeincapable of normal oxygen binding. As the chemical state of iron canchange from ferrous (Fe²⁺) to ferric (Fe³⁺), the three-dimensionalstructure of the globin part can change in a manner that allows watermolecules to bind to the heme pocket. Binding of a water molecule in theferric iron containing heme pocket affects light absorption of the hemepocket. The oxidized form of myoglobin with a water molecule in the hemegroup is referred to as metmyoglobin and its color is brown. Theoxidation of the iron atom is believed to result in a brown color. Hemeligands other than oxygen or water may also affect meat color. Forexample, the presence of carbon monoxide (CO) may cause fresh meat tohave a desirable bright red color similar to oxygen. Although it hasbeen suggested that nitric oxide (NO) can cause a dull red color (orstable pink color in the case of cured meat which also contains sodiumchloride), it has been discovered that in the absence of oxygen, NO mayproduce a desired bright red color similar to that caused by oxygen inuncooked meat, especially in fresh, raw, unprocessed or uncured meat. Ithas been discovered that the development of this desired bright redcolor may take many hours and typically may take from 1 to 5 days andthat initially, the meat color in a vacuum package having an oxygenbarrier may turn to an undesirable brown until the unexpectedtransformation to the desired red takes place.

Other variables that affect the stability of the globin portion alsoaffect the affinity of the heme group for oxygen and the tendency of thechemical state of the iron atom to become oxidized. Acidity and hightemperature, such as that associated with cooking, can denature theglobin part thus leading to instability of the heme group. In theabsence of stabilizing ligands, the oxidation of the heme iron isautomatic when the globin is denatured.

Packaging Inserts

A packaging insert is an article that is incorporated in a packaged foodproduct which is not an integral part of the packaging film that formsthe outer wrapper. A packaging insert, when incorporated in a packagedfood, is in contact with the food product. Packaging inserts can serveany of a variety of purposes including absorbing liquids, cushioningsharp or rough surfaces such as bones, protecting a surface on the foodproduct, modifying the atmosphere within the package, or containing allor a portion of the food product such as the giblets inside of poultry.Examples of packaging inserts include absorbent and non-absorbent pads,soaker pads, purge control pads, puncture resistant inserts, packets,pouches, sachets and trays.

Referring to FIG. 2, in one embodiment, the packaging insert 20 shown ina side-on view, has a layer 22 comprising a myoglobin blooming agent anda meat contact surface 24. Referring to FIGS. 3 a and 3 b, in anotherembodiment, the packaging insert 30 comprises a layer 34 comprising anabsorbent material, adjacent to a layer 32 comprising a myoglobinblooming agent and having a meat contact surface 36. The layer 32 may beperforated or otherwise fluid pervious. In other aspects, the layer 32may be fluid impervious. In some aspects, the layer 32 is coextensivewith the layer comprising an absorbent material. In other aspects, thelayer 32 extends beyond the perimeter of the layer comprising anabsorbent material as illustrated in FIGS. 3 a and 3 b.

Referring to FIGS. 1 a and 1 b, in yet another embodiment of the presentinvention, the packaging insert is represented generally by referencenumber 10 having a layer 12 comprising a myoglobin blooming agent and alayer 14 with a layer 16 comprising a myoglobin blooming agentpositioned therebetween layer 14 and 12. Layer 12 and layer 14 are theouter layers of insert 10 and can be film, non-woven, or paper. Layer 12and 14 are bonded together at least partially around a periphery 18 ofthe packaging insert. Either or both of layers 12 and 14 may be fluidpermeable and may include holes, microperforation, or slits. Eitherlayer may be liquid impermeable. Examples of appropriate layers include,but are not limited to, polyethylene, polypropylene, polyester, or anycombinations thereof.

In one aspect of the first embodiment, the packaging insert comprises afirst layer comprising a myoglobin blooming agent. The first layer maybe a film, a web, a non-woven, a paper, or other suitable material. Insome aspects, the first layer comprises a polymeric material. Examplesof polymeric materials include polymers and polymeric blends of thefollowing monomers: mono-olefins and conjugated di-olefins, e.g.,ethylene, propylene, 1-butene, isobutene, 1,3-butadiene, isoprene andother aliphatic mono and di-olefins; halogen substituted olefins, e.g.,vinyl chloride, vinylidene chloride; mono/vinylidene aromatic compounds,e.g., styrene, alpha methylstyrene, chlorostyrene, other aromaticolefins; and other unsaturated monomers such as acryonitrile, acrylamideand the like. Polyamide polymers, e.g., nylon 66 and nylon 6,polyesters, urethanes, copolyether esters, and copolyether amides mayalso be used. Preferably the film comprises polyethylene, polypropyleneor polyester. In some embodiments, it may be desirable to use polymersthat offer high elasticity with increased ability to expand. Thisproperty may be desirable to accommodate the swelling of the absorbentlayer after absorbing liquids. Polyurethane, metallocene polyethylenes,and block copolymers (synthetic rubber), which can be cast or blown intoa film or extruded into a non-woven (spunbond, meltblown, or anycombinations thereof) either individually, as a co-extrusion or abicomponent formation, or in a blend, may be employed when highelasticity is desired. The film may be monolayer or multilayer.Multilayer films may comprise between 2 and 14 layers. The film can beany suitable color, with white or black preferred.

The first layer comprises a myoglobin blooming agent. The myoglobinblooming agent may be coated on the meat contact surface of the firstlayer by any suitable method including spraying, dusting or dipping. Themyoglobin blooming agent is preferably evenly dispersed over the meatcontact surface of the first layer.

In other embodiments, the myoglobin blooming agent may be incorporatedwithin the first layer by any suitable method. When the first layer is afilm or web, the myoglobin blooming agent may be mixed with a basepolymer prior to extrusion of the film or web. For example, the basepolymer can be a polyolefin, such as polypropylene, polybutylene,polyethylene, and may be very low density polyethylene (VLDPE), ultralow density polyethylene (ULDPE) linear low density polyethylene(LLDPE), low density polyethylene (LDPE).

Melt blending is a preferred method of mixing the base polymer and themyoglobin blooming agent. The individual component materials may becombined in a high intensity mixing device such as an extruder. The basepolymer is melted to form a viscous liquid or “melt.” The myoglobinblooming agent may be combined with the polymer before, during, or aftermelting. The high intensity mixing device is used to attempt touniformly disperse the myoglobin blooming agent within the base polymer.The quality and functionality of the dispersed additive can depend uponthe myoglobin blooming agent and the base polymer as well as the mixingdevice. It is desirable to achieve good mixing for uniform dispersion ofthe myoglobin blooming agent within the melt; the presence of poorlywetted particle agglomerations is undesirable.

Depending on the myoglobin blooming agent, the myoglobin blooming agentmay be either directly added to the base polymer melt or provided in anaqueous solution that is added to the polymer melt. For a water solublematerial, it has been found that providing the myoglobin blooming agentas an aqueous solution provides better distribution of the compoundwithin the polymer. An aqueous solution is prepared from the myoglobinblooming agent. The concentration of the myoglobin blooming agent ispreferably close to the saturation concentration of the aqueoussolution. The solution preferably includes between about 20 wt % andabout 42 wt % of the myoglobin blooming agent. The aqueous solutionincluding the myoglobin blooming agent and water is introduced into apolymer melt. This is typically performed in an extruder. The basepolymer is preferably at a temperature above a melting point of the basepolymer so as to form a polymer melt. The polymer is typically heated toa temperature above about 300° F. The solution is mixed with the polymermelt in the extruder to form a blend. At least a portion of the watervaporizes and vents from the extruder. The blend is extruded from theextruder. The blend is typically extruded into pellets, but may beextruded directly as a film or web.

The myoglobin blooming agent may be added to the same extruder used toform the film or web. More commonly, the compound is first mixed withthe base polymer to form a masterbatch. Pellets from the masterbatch areconvenient for subsequent use in fabricating articles. Thus, afterdispersion of the myoglobin blooming agent in the mixing device iscomplete, the melt is discharged through a shaping device or die that isused to prepare pellets of the masterbatch. To form the convenientpellet shape, the die typically is outfitted with circular orificesthrough which the molten compound flows. The circular orifices formcontinuous cylinders of the compound that are subsequently cut to formpellets. Pellets from the masterbatch may then mixed with the basepolymer or another polymer during the film forming process.

Heat resistant layers generally comprise the outer or inner layer of amultilayer plastic film formed from a coextrusion process. Reference tothe outer layer of a multilayer film is intended to refer to the outercircumferential layer of a tube of plastic film formed via an extrusionprocess. Bags can be formed by heat sealing a tube of plastic multilayerfilm. An absorbent pad may be placed in such bags to form a soaker padwith a plastic film covering. Heat resistant layers are useful toprevent simultaneous heat sealing between overlapping bags during heatsealing processes.

The multilayer films can comprise an adhesion or tie layer, which can beselected to promote the adherence of adjacent layers to one another in amultilayer film. The adhesion layer is preferably formulated to aid inthe adherence of one layer to another layer without the need of usingadhesives by virtue of the compatibility of the materials in that layerto the adjacent layers. In some embodiments, adhesion layers comprisematerials found in both the adjacent layers.

The multilayer films can comprise a sealant layer. A sealant layer ispreferably formulated and positioned to form a heat seal. The sealantlayer may comprise either the inner layer or the outer layer of amultilayer plastic film formed from a coextrusion process and allows amultilayer film to be formed into bags. An absorbent pad may be placedin such bags to form a soaker pad with a film covering.

In one aspect of the present invention, a layer may comprise anabsorbent material. Packaging inserts comprising a layer comprising anabsorbent material are fluid absorbing packaging inserts which are oftenreferred to in the art as “soaker pads,” or “purge control pads.” Soakerpads are well known in the art and may be made from a variety ofmaterials. Soaker pads may be manufactured in a wide variety of sizesand shapes (e.g., rectangular, oblong, trapezoidal, triangular,circular, oval, donut-shaped, cone, rod, hourglass, “T”-shaped,asymmetric, etc.), and can be adapted to any type and shape of foodproduct being packaged, although rectangular configurations are mostcommon.

The layer comprising an absorbent material may or may not include amyoglobin blooming agent. The absorbent material can be any materialcapable of absorbing liquids, in particular food product fluids, and ispreferably approved or approvable for use with food products, inparticular meat products. Absorbent materials can be made frommanufactured or synthetic fibers, or natural fibers, or a combinationthereof, and either woven or non-woven. Non-woven refers to a web thathas a structure of individual fibers or threads which are interlaid, butnot in any regular, repeating pattern. The individual fibers may besecured or attached to each other. Many types of non-woven fabrics areknown in the art. One such suitable fabric is a 40 g per square meterbi-component continuous filament which is pressure and temperaturebonded. The filament can be made of a polyester core with a polyethylenesheath and this type of material is known. The filament may comprise adifferent type of sheath plastic such as polypropylene or apolypropylene polyethylene co-polymer. These filaments are desirablebecause a strong heat seal can be formed in the non-woven fabric. Thesenon-woven fabrics have a good random distribution of the fibers toensure suitable pore size or holes in the fabric to preventsuperabsorbent polymer granules from squeezing through the fabric.

The absorbent material may be tissue including tissue wraps and tissuelaminates, absorbent sponge materials including cellulose sponge,absorbent foams including open cell and closed cell foams, polymericmaterial including superabsorbent polymers, and other absorbents.

The layer of the soaker pad comprising an absorbent material maycomprise a single type of absorbent material or mixture. Although manytypes of absorbents are known and used in soaker pads, superabsorbentpolymers, which can absorb many times their weight in liquid, arepreferred. Superabsorbents can be made from chemically modified starchand cellulose, poly(vinyl alcohol), poly(ethylene) oxide, andcross-linked poly(acrylic acid). Examples include, but are not limitedto, sodium salts of cross-linked poly(acrylic acid)/polyalcohol andsodium carboxy methyl cellulose cross-linked with a suitable aluminumcompound. These polymers are hydrophilic and have a high affinity forwater. The polymers are typically dried and milled into granular solidswhich swell to a gel upon absorbing water.

Other superabsorbent materials include superabsorbent composites ofsuperabsorbent polymer granules adhered with one or more binders and/orplasticizers, airlaids with superabsorbent, fibrous or foam structuresthat have been coated or impregnated with a superabsorbent, nonwovenfabric structures such as thermal bond or resin bond that containsuperabsorbent particles or fibers, absorbent structures containingsuperabsorbent material formed and/or crosslinked in-situ, absorbentgelling materials including gelatinized starches, gelatin, dextrose, orany combinations thereof.

Other absorbent material in include cellulosic materials. Examples ofcellulosic materials include wood pulp (known in the art as wood fluff),rayon, needle punctured rayon, lyocell (TENCEL®), cotton, rag paper;pulp paper blotter, creped cellulose wadding, chemically stiffened,modified or cross-linked cellulosic fibers including, for example,carboxymethylcellulose (CMC) and salts thereof, hydroxyethylcellulose,methylcellulose, and hydroxypropylmethylcellulose.

Absorbent materials also include high yield pulp fibers, flax, milkweed,abaca, hemp, cotton or any of the like that are naturally wet resilientor any wood pulp fibers that are chemically or physically modified,e.g., cross-linked or curled, that have the capability to recover afterdeformation in the wet state, as opposed to non-resilient fibers whichremain deformed and do not recover after deformation in the wet state.Wet-resistant bonds are fiber-to-fiber bond sites that are resistant todisruption in the wet state resulting in improved wet tensile strength.As used herein, “high yield pulp fibers” are those paper making fibersproduced by pulping processes providing a yield of about 65 percent orgreater, more specifically about 75 percent or greater, and still morespecifically from about 75 to about 95 percent. Such pulping processesinclude bleached chemithermomechanical pulp (BCTMP),chemithermomechanical pulp (CTMP), pressure/pressure thermomechanicalpulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp(TMCP), high yield sulphite pulps, and high yield kraft pulps, all ofwhich leave the resulting fibers with high levels of lignin. Thepreferred high yield pulp fibers are characterized by being comprised ofcomparatively whole, relatively undamaged tracheids, high freeness (over250 CSF), and low fines content (less than 25 percent by the Britt jartest).

The absorbent material may also comprise synthetic polymers, fibers, ormaterials which may or may not be used in combination with cellulose orcellulose derivatives. One example of such material is a pulp coformmaterial, an example of which is described in U.S. Pat. No. 4,929,480.In this example, the pulp coform material comprises wood pulp fluff andextruded thermoplastic synthetic fibers. The synthetic fibers aretypically meltblown thermoplastic materials such as polypropylene orpolyethylene fibers.

The absorbent material may comprise an additive. Additives includebinder fibers, bactericidal agents, and additives to improve absorbency.Additives which improve absorbance include clays (such as attapulgite,montmorillonite (including bentonite clays), hectorite, sericite,kaolin), mineral compositions such as diatomaceous earth, inorganicsalts, polymeric flocculating agents, CMC, starch, dextrose, gelatin,natural gums (such as xanthan, guars, and alginates), inorganic buffers,superabsorbent polymers in the form of in the form of a fiber, powder,flake, particle, or granule, or other form includingcarboxy-methyl-cellulose superabsorbent compounds and acrylicsuperabsorbent (acrylic acid and sodium acrylate copolymer) compounds.Carboxymethylcellulose is a preferred additive.

Other additives include binder fibers which facilitate binding of theabsorbent layer to the top or bottom sheet. Binder fibers includecoextruded materials such as polypropylene/polyethylene,polyester/polyethylene, and polyester/polypropylene fibers.

The absorbent material may also contain bactericidal agents. Examples ofbactericidal agents include broad spectrum antibiotics such astetracyclines, e.g., chlorotetracycline and oxytetracycline; penicillin;sorbic acid; alkyl substituted or alkyl aryl substituted quaternaryammonium compounds such as trimethyldodecylammonium chloride,cetyltrimethylammonium bromide and alkyldimethylbenzylammonium chloride;chlorine containing compounds such as the hypochlorites andchloroamines; iodine compounds such as sodium hypoiodite; phenol and itsderivatives such as pentachlorophenol and orthophenylphenol;dehydroactic acid; peroxygen compounds such as hydrogen peroxide,potassium persulfate, peracetic acid and sodium perborate.

The additive may be applied to the absorbent material in any preferredmanner. Two basic methods are firstly wetting the absorbent materialwith an aqueous solution of the additive and then drying, or, secondly,mixing or impregnating the absorbent material with a dry agent. Ofcourse, any method of placing the additive within the absorbent materialthat will not adversely affect product quality is acceptable.

When the packaging insert comprises more than one layer, the layers aredesirably compressed together to minimize the bulk or thickness of theabsorbent insert. Passing multiple layers simultaneously through one ormore rollers or nips mechanically compresses the layers in theirentirety, and the equipment used to do this is often termed a calendaror supercalender. In addition to calendaring or supercalendering, thelayers may be compressed using flat platen presses or fabric nips.

When the packaging insert comprises more than one layer, the layers maybe adhered by any suitable manner known to one skilled in the art,including, for example, mechanical crimping, adhesively bonding, sewing,pressure bonds, ultrasonic bonding, or heat sealing. The layers may beadhered throughout, at specific points or along the periphery of thelayers.

In one embodiment, when the layer comprising an absorbent material is atleast partially disposed between two other layers, the two other layersmay be attached partially along peripheral edges, or portions of theperipheral edges. For example, when the sheets are rectangular, it maybe desirable to attach the sheets along two, three or all four edges.The sheets may be adhered together by pressure, adhesive, ultrasonicbonding, mechanical crimping, sewing and the like. These methods providea solid bond capable of resisting bursting. Spraying or otherwiseapplying glue or other adhesive on surfaces adjacent the edges of thesheet, thermal sealing, such as a hot melt adhesive, or by theapplication of heat and pressure may also be used. A wax or other foodgrade sealant may be applied, or the film layers may be hermeticallysealed. An embossing, knurling, or point-bonding pattern can be used foreven stronger and more flexible bonds than simple flat bonding.

Thermal sealing can provide a strong seam with a minimal amount ofmaterial from the top and bottom sheets. Using adhesives to bind the topsheet to the bottom sheet typically requires between about 0.25 inchesto about 0.5 inches of material from the top and bottom sheets to createa sufficient seal. However, seals formed by this traditional method areprone to failure when the absorbent layer absorbs fluid and exertsstress on the seal. Thermal sealing provide for strong sealing usingonly about 0.125 inches to about 0.5 inches of material to create theseams.

Heat sealing of film, non-woven, or paper sheets may be desirablyenhanced by using a film co-extruded with, a non-woven bi-componentwith, or a paper coated with a low-melt material. Generally, low-meltmaterials, such as polymers, are on one side of the sheet and arepositioned toward the absorbent layer. The low-melt materials can be onboth sheets to be sealed or on only one of the sheets. It is preferredthat both sheets to be sealed have low-melt materials. A preferredco-extruded film is of a high-density polyethylene (HDPE) with anethylene vinyl acetate (EVA) component on the low-melt side. A preferredthickness for these films is between about 0.0075 inches to about 0.003inches. The layers can be corona treated to promote ink anchorage andseam bonding. Techniques for sealing the layers include conventionalheat/pressure, thermal impulse sealing, radiant surface heat followed bypressure or heat/pressure, ultrasonic sealing, or any combinationsthereof. An example of a combination of techniques is ultrasonic sealingpreceded by thermal or radiant heat application.

Corona treatment involves exposing a gas situated in an air gap betweenan electrode assembly and a treater roll to a very strong electricalfield to break down and ionize the gas, which enables the gas moleculesto become conductive. When a sufficient number of gas molecules havebecome ionized, a conductive path is generated between the electrodescausing a sudden discharge across the path resulting in a bright flashor arc, which is interrupted by a solid dielectric barrier of sufficientmaterial. This causes, instead of a hot localized arc, a cooler diffuseglow. The soft colored discharge is called a corona and indicates theincomplete breakdown of the gas. Substances to be treated, such as thesurfaces of film, non-woven, and paper sheets in the absorbent packaginginsert of the present invention, are passed into the corona field whereit is exposed to the high voltage discharge and the bombardment of highenergy particles. The corona field has the ability to break polymerbonds, cause micro-pitting, and deposit an induced surface charge withextremely high levels of strong oxidizing agents onto the substance.Corona treatment can alter the surface characteristics of the substanceallowing for enhanced surface adhesion and acceptance of printing inks,adhesives, coatings, and the like.

In one aspect of the present invention, a layer may be fluid pervious.For example, when the packaging insert comprises a layer comprising anabsorbent material, it may be desirable for the layer to be fluidpervious such that fluid can reach the layer comprising the absorbentmaterial, particularly when it is encapsulated by two other layers. Aliquid permeable layer may be rendered permeable due to the nature ofthe material or the process by which it is made. For example, permeablelayers can be prepared from paper and non-woven fibers. Other layers maybe made permeable by post-processing methods to provide holes, slits,perforations, microperforations (for example less than about 0.01inches), and the like, in the sheet. U.S. Pat. No. 6,270,873 describesan absorbent packaging insert with microperforations.

In other aspects of the present invention, it may be desirable to use aliquid permeable layer, a liquid impermeable layer, a layer comprisingan absorbent material or a combination thereof. For example, anabsorbent packaging insert may comprise a layer having a meat contactsurface, wherein the layer is substantially liquid impermeable, servingas a hydrophobic barrier to the food product with respect to reversemigration of liquids from the layer comprising the absorbent material tothe meat product. In other aspects, a layer having a meat contactsurface may be fluid permeable to allow fluids on the meat contactsurface to reach the absorbent layer. The liquid permeable layer maycontain holes, slits, perforations, microperforations (for examplesmaller than about 0.01 inches), and the like, thereby allowing fluidfrom the meat product to penetrate through the permeable layer to theadjacent absorbent layer.

In other aspects of the present invention, a layer comprising awater-soluble resin is provided. Suitable water-soluble resins which maybe used in the invention are described in Davidson and Sittig,Water-Soluble Resins, Van Nostrand Reinhold Company, New York (1968),herein incorporated by reference. The water-soluble resin should haveproper characteristics such as strength and pliability in order topermit machine handling. Preferred water-soluble resins includepolyvinyl alcohol, cellulose ethers, polyethylene oxide, starch,polyvinylpyrrolidone, polyacrylamide, polyvinyl methyl ether-maleicanhydride, polymaleic anhydride, styrene maleic anhydride,hydroxyethylcellulose, methylcellulose, polyethylene glycols,carboxymethylcelulose, polyacrylic acid salts, alginates, acrylamidecopolymers, guar gum, casein, ethylene-maleic anhydride resin series,polyethyleneimine, ethyl hydroxyethylcellulose, ethyl methylcellulose,hydroxyethyl methylcellulose. Lower molecular weight water-soluble,polyvinyl alcohol film-forming resins are generally, preferred.

The generally preferred water-soluble, polyvinyl alcohol film-formingresins should, in addition to low weight average molecular weights, havelow levels of hydrolysis in water. Polyvinyl alcohols preferred for useherein have a weight average molecular weight between about 1,000 andabout 300,000, and preferably, between about 2,000 and about 150,000,and most preferably, between about 3,000 and about 100,000, includingall ranges subsumed therein.

Even further, it is within the scope of this invention to includepolyvinyl alcohol films which are copolymers, such as films preparedfrom vinyl acetate and methacrylic acid precursor monomers. Preferredcopolymers typically comprise less than about 15.0% by weightmethacrylic acid units in their backbone.

Various changes and modifications may be made without departing from thescope of the invention defined herein. For example, it is alsocontemplated that packaging inserts are provided in the form of sachetsor “tea bags” which may or may not include a myoglobin blooming agentgas-releasing powder contained therein. The sachets may includeabsorbent or non-absorbent monolayer or multilayer webs as describedherein. Preferably, the sachet is placed adjacent to the packagedproduct. When water or other fluids permeate into the sachet, a gas maybe generated and released into the atmosphere surrounding the product.The gas released alters the atmospheric conditions within the package.Preferably, the gas comprises a gaseous myoglobin blooming agent, morepreferably, carbon monoxide, carbon dioxide, sulfur monoxide, nitrousoxide, nitric oxide or combinations thereof, and most preferably, nitricoxide.

The above examples are illustrative only, and should not be interpretedas limiting since further modifications of the disclosed embodimentswill be apparent to those skilled in the art in view of this teaching.All such modifications are deemed to be within the scope of theembodiments disclosed herein.

Puncture Resistant Packaging Inserts

A puncture resistant packaging insert is a non-shrinkable article usedto prevent the puncture of a packaging film or other packaging means bysharp portions or rough surfaces of the food product, such as bone partsor other protruding parts of the meat product. In addition, the punctureresistant insert can also prevent puncture from exterior forces appliedagainst such sharp parts of the meat product. Puncture resistant insertsare resilient and may be conformable to the sharp portion of the meatproduct which they protect. Examples of puncture resistant insertsinclude cushion pads including foams, wax impregnated fabrics or webs,puncture resistant webs, and plastic bone caps.

Referring to FIG. 4, a puncture resistant packaging insert 40 has a foodcontact surface 42 which covers the sharp or rough portion of the meatproduct and also contacts the myoglobin containing meat. The foodcontact surface 42 of the puncture resistant packaging insert comprisesa myoglobin blooming agent. The puncture resistant packaging insert mayoptionally have prongs 44 that help to maintain the location of theinsert over the sharp or rough portion of the meat. FIG. 8 illustrates apuncture resistant packaging insert 50 covering the bone 52 of a meatsuch as a ham bone.

Referring to FIG. 9, a puncture resistant packaging insert 92 isincorporated in a bag 94 for packaging meat products. Puncture resistantpackaging insert 92 is formed of a puncture resistant polymer such asnylon, and is illustrated as a rectangular patch, but any suitable shapeor geometry may be chosen for the puncture resistant packaging insert.FIG. 10 illustrates a cross-sectional view of bag 94 along line 91-91.The bag comprises a front wall 102 and back wall 104. The punctureresistant packaging insert 92 has a food contact surface 106 comprisinga myoglobin blooming agent.

Puncture resistant packaging inserts may be made from a variety ofmaterials including paper, paper laminates, cloth or fabrics includingcheesecloth, webs, polymers and plastics. Examples of puncture resistantpolymers include nylons, polyesters, polyolefins, such as, polypropyleneand polyethylenes, including ultra low density polyethylene and linearlow density polyethylene. Puncture resistant packaging inserts may alsobe formed of resilient plastic foam materials including foams formedfrom polyethylene, polypropylene, ethyl cellulose, cellulose, urethaneand vinyl. Preferably when used with vacuum packaging processes, foamshave closed cell structures. Other puncture resistant packaging insertsinclude wax impregnated cloths or paper. Suitable waxes include lowmelting food grade petroleum wax and paraffin. Alternatively, thepuncture resistant packaging insert may be a hard plastic disk or capthat covers the bone or other sharp or rough portion of the foodproduct.

The puncture resistant packaging insert has a food contact surface whichmay comprise a myoglobin blooming agent. The myoglobin blooming agentmay be coated on the meat contact surface of the puncture resistantpackaging insert or it may incorporated within the puncture resistantpackaging insert such that the myoglobin blooming agent is evenlydispersed throughout the meat contact surface. When the myoglobinblooming agent is coated on the meat contact surface, it may be done soby any suitable means including spraying, dusting or dipping.

When the myoglobin blooming agent is incorporated into the punctureresistant packaging insert, it may done so by an suitable means, forexample by incorporation in the cloth, foam, wax, and the like.Depending on the myoglobin blooming agent, the myoglobin blooming agentmay be either added during the manufacture of the puncture resistantinsert, for example, blended or incorporated into the polymer, fabric,or wax materials before the puncture resistant insert is formed.Alternatively, the myoglobin blooming agent may be incorporated into thepuncture resistant packaging insert after the insert has been formed.For example, a solution of the myoglobin blooming agent can be formed ina suitable solvent. Depending on the myoglobin blooming agent and insertcomposition, an aqueous solution may be suitable. The insert is dippedin the solution such that the solution penetrates the insert, inparticular, the food contact surface of the puncture resistance insert.The insert is then dried, thereby incorporating the myoglobin bloomingagent in the puncture resistant insert. This method is useful forpuncture resistant packaging inserts made from porous materials or othermaterial that can likewise absorb liquids including foams, fabrics,papers and webs.

Food Packages

In a second embodiment, food packages are provided that comprise apackaging insert and a fresh meat product.

“Meat” or “meat product” refers to any myoglobin or hemoglobincontaining tissue from livestock such as beef, pork, veal, lamb, mutton,chicken or turkey; game such as venison, quail, and duck; and fish,fishery or seafood products. The meat can be in a variety of formsincluding primal cuts, subprimal cuts, and retail cuts as well asground, comminuted or mixed. The meat or meat product is preferablyfresh, raw, uncooked meat, but may also be frozen, hard chilled orthawed. It is further believed that meat may be subjected to otherirradiative, biological, chemical or physical treatments. Thesuitability of any particular such treatment may be determined withoutundue experimentation in view of the present disclosure. As long as themyoglobin blooming agent is effective to promote, develop, enhance ormaintain a desirable color, it may be advantageously employed to suchend. Preferably the meat is less than 20 days post mortem. Morepreferably, the meat is less than 12 days or even 6 days or less postmortem.

Primal cuts of meat are also termed wholesale cuts and both terms referto large sections of a carcass that are usually sold and/or shipped tobutchers who further subdivide the primal into subprimals and individualretail cuts for sale to consumers. Examples of primal cuts of beef are:round; rump; loin end; flank; short loin; plate; rib; brisket; shank;and chuck. Examples of pork primals include: loin; leg; shoulder; andbelly.

Subprimals are intermediate in size and may be divided further intoretail cuts or are sometimes sold as retail cuts. Beef subprimalsinclude: arm; blade; ribs; beef plate; top round; bottom round; ribs;top butt; bottom butt; tenderloin; and top loin. Pork subprimalsinclude: butt shoulder; picnic shoulder; center cut; sirloin; butt end;shank end; side pork and side rib.

Retail cuts of meat are consumer cuts made by dividing wholesale cutsinto smaller pieces. Examples of retail cuts of beef include: steakssuch as round, top round, cubed, sirloin, t-bone, porterhouse, filetmignon, rib eye, rib, skirt, flank, and tip; roasts such as blade, pot,and chuck; corned brisket; fresh brisket; stew beef; short ribs; kabobs;eye of round; rolled rump; shank cross cuts; steak rolls; ground beef;and beef patties. Examples of retail cuts of pork include: arm roastsand steaks; spareribs; bacon; salt pork; ham; ham steaks; ham slices;pork tenderloin; chops; cutlets; fat back; sausage; links; and groundpork.

“Fresh meat” means meat that is uncooked, uncured, unsmoked andunmarinated. “Fresh meat” includes post mortem meat that has beenphysically divided, for example, by cutting, grinding or mixing. Thereis no added salt in fresh meat that has not been enhanced. Naturallyoccurring sodium typically is less than 50 mg/100 g of meat and accountsfor a salt content of less than about 0.15 weight %, preferably lessthan 0.128 weight %. Values of sodium are in a database for nutritionalcomposition of meat called the “National Nutrient Data Bank”, and thedata is published in Agriculture Handbook No. 8, “Composition ofFoods—Raw, Processed, Prepared” referred to in the industry as “Handbook8,” both of which are hereby incorporated by reference.

“Enhanced meat” means meat that has added water mixed with otheringredients such as sodium chloride, phosphates, antioxidants, andflavoring, e.g., to make meat moist, more tender and to help enhanceshelf-life. Fresh beef, pork or poultry after being “enhanced” wouldtypically contain 0.3-0.6 weight % salt (sodium chloride).

“Processed meat” means meat that has been changed by heat and chemicalprocesses, e.g., by cooking or curing. Cooked ham, hot dogs, and lunchmeat are examples of cured processed meat.

“Uncured processed meats” are processed meats that do not containnitrites or nitrates. Uncured processed meats would typically containgreater than 1.0% by weight, typically 1.2-2.0 weight %, sodium chloride(salt). Cooked roast beef and bratwurst are examples of uncuredprocessed meat.

“Cured meat” means meat that is preserved through direct addition ofnitrite (or nitrate which is converted to nitrite), e.g., having atleast 50 ppm sodium nitrite and at least 1% by weight added salt, i.e.,sodium chloride, for the purpose of preservation by retarding bacterialgrowth. Nitrites, nitrates or blends thereof are commonly present withsodium chloride in curing compositions. “Uncured meat” does not containadded nitrite or nitrate. Wet cured meats are soaked in salt brine. Drycured meats have salt applied to the surface. Injection cured meats havethe curing salts (cure) applied by needle injection into the meat.

Cured processed meats often have 2-3.5 weight % salt. A brine content of3.5-4.0 weight % (2.6-3.0% on a weight basis in treated meat) as thelevel of sodium chloride salt (potassium chloride may be substituted forsome or all of the NaCl) is needed in processed meat to adequately slowdown bacterial growth to permit 60-90 day shelf life, although othermeans of preservation may also be employed to maintain shelf life atreduced salt levels. According to Pegg, R. B. and F. Shahidi, 2000,Nitrite Curing of Meat. Food & Nutrition Press, Inc., Trumbull, Conn.,cured meats may have typical salt levels of 1.2-1.8 weight % in bacon,2-3 weight % in hams, 1-2 weight % in sausages and 2-4 weight % injerkies. It is believed that fresh meat such as beef, pork and poultryhas no nitrite or nitrate naturally occurring or added. The UnitedStates Department of Agriculture (USDA) permits ingoing nitrite andnitrate for cured and processed meat at a level up to a maximum of 625ppm sodium nitrite or 2,187 ppm sodium nitrate in dry cured products. Inother applications levels have different limits, e.g., in typical cookedwhole muscle meat products the limit as sodium nitrite is 156 ppm and incomminuted meats, 200 ppm. The maximum nitrite usage level in hot dogsor bologna is typically 156 ppm, while that for bacon is 120 ppm. Sodiumascorbate (or similar compounds) may be present in these cures.

In Europe, it is believed that the minimum level of salt and nitriterequired by law for curing is 1.0 weight % and 50 ppm respectively. TheUSDA has stated: “As a matter of policy, the Agency requires a minimumof 120 ppm of ingoing nitrite in all cured “Keep Refrigerated” products,unless the establishment can demonstrate that safety is assured by someother preservation process such as thermal processing, pH or moisturecontrol. This 120 ppm policy for ingoing nitrite is based on safety datareviewed when the bacon standard was developed.” (See, “ProcessingInspectors' Calculations Handbook”, Chapter 3, p. 12, revised 1995). TheHandbook also states: “There is no regulatory minimum ingoing nitritelevel however 40 ppm nitrite is useful in that it has some preservativeeffect. This amount has also been show to be sufficient for color-fixingpurposes and to achieve the expected cured meat or poultry appearance.”

The meat product can be any meat suitable for human consumption thatcontains a myoglobin like molecule. References to total myoglobin in ameat product refer to the amount of the myoglobin like molecules thatare physiologically present in the meat tissue prior to harvesting forhuman consumption. Specific meat products contain a level of myoglobinsufficient to provide its characteristic color. Examples of suitablefresh meat cuts include beef, veal, pork, poultry, mutton, and lamb. Theconcentration of myoglobin varies in these different types of meatproducts. For example, beef typically contains about 3-20 mg ofmyoglobin per gram of meat, pork contains about 1-5 mg myoglobin pergram of meat, chicken contains less than about 1 mg myoglobin per gramof meat. Thus, the concentration of total myoglobin compounds in theabove described meat products is typically between about 0.5 mg and 25mg of myoglobin compounds per gram of the meat product.

In fresh meat (postmortem muscle tissue), oxygen can continuallyassociate and disassociate from the heme complex of the undenaturedmyoglobin molecule. It is the relative abundance of three forms of theundenatured muscle pigment that determines the visual color of freshmeat. They include purple deoxymyoglobin (reduced myoglobin), redoxymyoglobin (oxygenated myoglobin); and brown metmyoglobin (oxidizedmyoglobin). The deoxymyoglobin form typically predominates immediatelyafter the animal is slaughtered. Thus, freshly cut meat can have apurple color. This purple color can persist for a long time if thepigment is not exposed to oxygen. Cutting or grinding exposes thepigment to oxygen in the atmosphere, and the purple color can quicklyconvert to either bright red (oxymyoglobin) or brown (metmyoglobin).Thus, although deoxymyoglobin is technically indicative of fresher meat,it is the red or “bloomed” meat color that consumers use as theirprimary criterion for perceiving freshness. It is believed withoutwishing to be bound by the belief that the preferred red color of freshmeat occurs when at least 50% of the deoxymyoglobin molecules areoxygenated to the oxymyoglobin state. Changes in the relative percentageof each of these forms can continue to occur as fresh meat is exposed tooxygen for longer periods of time. The immediate conversion of thepurple color to the desirable bright red or undesirable brown can dependon the partial pressure of oxygen at the surface. The purple color isfavored at the very low oxygen level, and can dominate at oxygen levelsof 0-0.2% by volume. The brown color is favored when the oxygen level isonly slightly higher (0.2% to 5.0%). Consumer discrimination typicallybegins when the relative amount of metmyoglobin is 20%. A distinctlybrown color is evident at 40% metmyoglobin, which typically renders themeat unsaleable even though it remains nutritious and healthy forconsumption.

Certain biochemical reactions that occur in muscle tissue after deathcan also affect fresh meat color, such as the presence of activeglycolytic enzymes that convert oxygen to carbon dioxide. Reducingcoenzymes called metmyoglobin reductases present in meat convertmetmyoglobin back to deoxymyoglobin, and their activity is called “MRA”which is an abbreviation for metmyoglobin reducing activity. MRA can bedescribed as the ability of muscle to reduce metmyoglobin back to itsnatural deoxymyoglobin state. MRA is lost when the oxidizable substratesare depleted or when heat or acid denatures the enzymes. When theenzymes lose their activity or are denatured, the iron of the hemepigment automatically oxidizes to the metmyoglobin form, and the browncolor stabilizes and dominates. MRA persists for a period of time afterdeath depending on the amount of exposure of the meat tissue to oxygen.During this time oxygen is continually consumed by the meat tissue. Theoxygen consumption rate is referred to as “OCR”. When meat that has ahigh OCR is exposed to oxygen, the oxygen tension is reduced so rapidlythat the metmyoglobin is favored below the viewing surface. If it isclose to the viewing surface, the perceived color of the meat isaffected. The MRA is important to minimize this layer of metmyoglobinthat forms between the bloomed surface and purple interior. As the MRAwears out, the brown metmyoglobin layer thickens and migrates toward thesurface, thus terminating display life. When the MRA is high, themetmyoglobin layer is thin and sometimes not visible to the naked eye.

MRA and OCR relate to determining the types of packaging best suited forretail sale in order to prolong the desirable appearance of meat as longas possible. Hermetically sealed packages with films that are a barrierto oxygen will cause a low oxygen tension on the meat surface. Thus,metmyoglobin formation occurs and the viewing surface changes to anundesirable brown color. However, if the OCR is high enough to keepahead of the oxygen that migrates across the packaging film, and the MRAis good enough to reduce metmyoglobin that forms on the surface, thennative deoxymyoglobin replaces metmyoglobin. After a period of time, theperceived color changes from brown to purple. Both of these colors areunacceptable to the consumer. For this reason, vacuum packaging byitself has historically been an unacceptable format for case ready freshmeat although it is used to ship subprimal and other large cuts of meatfrom the slaughterhouse to retail butchers for further processing andre-packaging. On the other hand, vacuum packaging is the format ofchoice for cooked and cured processed meats where the myoglobin pigmentis denatured by heat. Heat from cooking causes the globin portion of thenitrosylated myoglobin molecule to denature and separate from the hemeportion. It is the dissociated nitrosylated heme complex that givescured and processed meats their characteristic color. When oxygen iseliminated from a cured processed meat package, the product's color andflavor can deteriorate slower than when oxygen is present. In thepresent invention it is advantageous to reduce or eliminate oxygen fromthe environment of the raw fresh meat in order to maximize thedevelopment of the preferred red color. A certain amount of oxygen maypenetrate the meat after slaughter and fabrication. This oxygen iseliminated by the OCR/MRA activities. Similarly, those activitiesfacilitate the dominance of the deoxymyoglobin form of the myoglobinmolecule. It is believed, but not wishing to be bound by the belief,that the OCR/MRA activities also facilitate the reduction of nitrite tonitric oxide when sodium nitrite is used as the myoglobin bloomingagent. In this case, the formation of deoxymyoglobin and nitric oxideallows for the development of nitroxymyoglobin. Oxygen itself is amyoglobin blooming agent because it causes the formation of oxymyoglobinas described earlier herein. However, oxygen interferes with thereactions that form deoxymyoglobin and nitric oxide. Therefore, it mayinterfere with the bloomed color development in the presence of nitrite.Thus, it is a preferred aspect of the present invention that an oxygenbarrier layer is selected and configured to protect the meat surfacefrom the ingress of atmospheric oxygen during the formation of thedesired bloomed meat color.

The absorbent packaging insert of the present invention can be shaped toconform to the desired packaging or container. The particular form ofthe food container and/or the packaging itself may comprise any one ofnumerous forms known to those skilled in the art such as, for example,wrapped trays, cardboard boxes, plastic containers, scalable bag, andthe like. With respect to packaged meat products, the absorbentpackaging inset is often placed over the central portion of a tray. Theabsorbent packaging insert may be sized to fit the tray as a singlecontinuous unit or configured to overlay the tray in sections. Theabsorbent packaging insert can be placed over the support tray prior toplacing the product thereover, or the absorbent packaging insert may bepermanently attached to the tray to prevent movement of the same inhandling. For example, the absorbent packaging insert may be adhesivelyattached to the supporting tray, or may be made an integral part of thetray itself.

Referring now to FIG. 5, a cross sectional schematic of a meatcontaining tray 50 is depicted. Tray 51 has a bottom 52 with integralside walls 52 a and 52 b supporting an absorbent packaging insert 66beneath a retail cut of meat 53 such as pork. The meat contact surface68 of the absorbent packaging insert comprises a myoglobin bloomingagent which to fix color on the meat bottom surface 61. Film 54 sealsthe top of the tray 51 and provides a hermetic seal 55 a and 55 b allalong the continuous flanges of the sidewall 52 a, 52 b. Alternatively,film 54 may drape over walls 52 a and 52 b and seal to bottom 52 of tray51 (not shown). The film 54 is either vacuum sealed or sealed in amodified atmosphere with the myoglobin blooming agent containing foodcontact surface 57 in intimate contact with meat surface 58. Meat sidesurfaces 59 a, 59 b are not in contact with the food contact layer 57but instead are exposed to an atmosphere 56 modified with a gas such ascarbon monoxide. The tray has an inside surface 60 on which theabsorbent packaging insert 66 rests.

Referring now to FIG. 6, a top view of a package 62 depicts a myoglobincontaining food 63 such as a bone-in cut of meat on a substrate andcovered under a vacuum skin packaging film 64 having a myoglobinblooming agent coated food contact surface in contact with the meat. Theabsorbent packaging insert is below the myoglobin containing food 63.The film is transparent to allow perception of the color and meatsurface characteristics.

Referring now to FIG. 7, a cross sectional schematic of a meatcontaining formed container 70 is depicted having a myoglobin containingcut of fresh meat 71 disposed in a thermoformed pocket 72 which is heatsealed to a non-oriented film 73 around the meat cut at heat seal 74 awhich is continuous and joins heat seal 74 b to form a hermetic vacuumpackage having a reduced oxygen atmosphere with intimate contact betweenthe myoglobin blooming agent containing surfaces of film 72 and 73. Anabsorbent packaging insert 76 is located between the myoglobincontaining fresh meat 71 and the non-orientated film 73. The meatcontact surface 78 of the absorbent packaging insert 76 is in contactwith the myoglobin containing meat.

Packaging Webs

The food packages further comprise an oxygen barrier packaging webcomprising a single-layer or multilayer film, sheet or combinationsthereof. Single-layer and multilayer packaging webs can have anysuitable composition or configuration and may include heat shrinkableand non-heat shrinkable oxygen barrier packaging materials. Preferably,the food packaging web fulfills multiple functional requirements whichmay be present in one or more or a combination of layers. For example, asingle layer web may combine the functions of oxygen barrier andmyoglobin blooming agent contact with one or more additional functionssuch as puncture resistance, abuse resistance, printability, moisturebarrier, heat sealability, transparency, high gloss, low toxicity, hightemperature resistance, low temperature flexibility, etc. Alternatively,multiple layers may be employed to add functionality. The presentinvention is adapted for use in a wide variety of commercially availablepackaging films such as those sold by: Curwood, Inc. under thetrademarks ABP, Clear-Tite, Cook-Tite, Perflex, Pro-Guard, Pro-Tite,Curlam®, Curlon® and Surround; and by others, e.g., marketed by Alcan,Asahi, Cryovac, Kureha, Vector, Pactiv, Printpack, Viskase and Wipak,under the trademarks or brand names Cryovac® T-Series, Cryovac® E-SealMaterials, Alcan Q® Series, Alcan Peel Rite™ Peel Systems, Alcan Q⁴Forming Films, Krehalon®, Alcan Mara Flex® Non-Forming Films, WipakCombitherm, Wipak Bialon, Wipak Biaxer, and Wipak Biaxop, A typicalbeneficial food packaging web according to embodiments of the presentinvention may have an interior surface food contact layer which alsoserves as a sealant layer, and a heat resistant and abuse resistantexterior surface layer with a core layer there between which comprisesan oxygen barrier material. Another common suitable web has adhesivelayers on either side of the core oxygen barrier layer to connect withthe surface layers.

In the present invention, oxygen barrier, food packaging webs mayinclude food contact surfaces which may or may not comprise a myoglobinblooming agent. A “food contact surface” refers to the portion of apackaging material that is designed to contact a packaged meat productsurface. Preferably, when the food packaging web includes a food contactsurface comprising a myoglobin blooming agent, the myoglobin bloomingagent is present in an amount effective to promote or maintain adesirable color after contact with a meat product. The myoglobinblooming agent (MBA) preferably will contact the meat surface in anamount sufficient to produce a desired red color which preferably doesnot penetrate to an undesirable depth of the food thickness underreduced oxygen conditions (this color may take awhile to develop, e.g.,1 to 5 days). Beneficially, the MBA may be present on the film foodcontact surface (or on the myoglobin-containing food product surface) inan amount of from about 0.01 to 3 to 5 to 10 μmoles/in² and inincrements of 0.1 μmole thereof. Greater or lesser amounts of MBA may beused, and the color intensity may thereby be varied depending upon therelative amount of intrinsinc myoglobin present in the meat.

The packaging webs may or may not be heat shrinkable as that term isgenerally understood in the industry. That is, if a web isnon-shrinkable, it and packages made therefrom may have 10% or less freeshrink in both the machine direction and the transverse direction at 90°C. or less as measured before the web has undergone thermoforming. Forsome applications, the non-shrinkable webs may have less than 5% shrinkat 90° in both the machine direction (MD) and the transverse direction(TD) as measured before the web has undergone thermoforming. For otherapplications, the non-shrinkable webs may have a free shrink as measuredbefore the web has undergone thermoforming at 90° C. of less than 2%,more preferably less than 1% in both the machine direction and thetransverse direction. In contrast, heat shrinkable webs may have a freeshrink at 90° C. of at least 10% in at least one direction. Preferably,heat shrinkable films have a total free shrink at 90° C. of at leastabout 30%, more preferably at least 40% or 60% or more.

Web Thickness

A packaging web may be a film, a sheet, or combination thereof.Preferably, a flexible film has a total thickness of less than about 10mil, more preferably the film has a total thickness of from about 0.5 to10 mil (12.7-254 microns (μ)). Semi-rigid sheets may have a totalthickness between about 10 mil to about 20 mil. Rigid sheets may have atotal thickness more than about 20 mil. Advantageously, packaging filmsmay have thicknesses from about 1 to 5 mil, with certain typicalembodiments being from about 1.5 to 3 mil. For example, entire single ormultilayer films or any single layer of a multilayer film can have anysuitable thicknesses, including 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mils,or any increment of 0.1 or 0.01 mil therebetween. Thicker and thinnerfilms are also provided. Although suitable webs for packaging foodstuffsas thick as 4 mil (101.6 microns) or higher, or as thin as 1 mil (25.4microns) or less may be made, it is expected that the most common webswill be between about 1.5-3 mil (38-76 microns). Especially preferredfor use as webs for food packaging are films where the multilayer filmshave thicknesses of between about 2 to 3 mil (50.8-76.2 microns). Suchfilms may have good abuse resistance and machinability.

Packaging Methods

In a third embodiment, packaging methods are provided. A number ofpackaging methods are known in the art, including modified atmospherepackaging, vacuum packaging, skin packaging and vacuum skin packaging.

“Reduced oxygen atmosphere” when referring to a packaged meat productrefers to a reduction in the partial pressure of oxygen in contact withthe packaged meat product, in comparison with the partial pressure ofoxygen in the Earth's atmosphere at standard temperature and pressure atsea level. Reduced oxygen atmosphere packages may include modifiedatmosphere packages where the oxygen partial pressure is less than thatof the Earth's atmosphere at standard temperature and pressure at sealevel, or vacuum packages, containing minimal gas pressure in contactwith the packaged meat. Modified atmosphere packaging may create asubstantially oxygen reduced environment where the oxygen content ofless than 3.0% oxygen v/v is desirable, and preferably less than 1.0%oxygen v/v. For processed meat, oxygen content of less than 0.5% v/v isdesirable.

“Vacuum packaging” refers to actively eliminating atmospheric gases,most specifically oxygen, from inside the package and sealing thepackage so that virtually no gas is able to permeate into the packagefrom outside the package. The result is a package with a minimum amountof oxygen gas remaining in contact with the meat inside the package. Theremoval of oxygen from the immediate environment of the product slowsdown bacterial and oxidative deterioration processes thereby keeping thequality of the meat fresher for a longer period of time.

“MAP” is an abbreviation for a “modified atmosphere package”. This is apackaging format where a gas is actively flushed into the headspace of apackage prior to sealing. In general, the gas is modified to bedifferent from that normally found in the earth's atmosphere. The resultis a package with a considerable volume of gas surrounding the viewingsurface of the product within the package. A fresh meat MAP can useeither an enriched-oxygen or an oxygen-free atmosphere to effectivelyextend shelf life.

“RAP” is an abbreviation for a “reduced atmosphere package.” It can be aform of MAP wherein the atmospheric gases are minimal so that thepackaging material makes physical contact with the internal contents.RAP can also be a form of vacuum packaging where the atmosphere is notcompletely evacuated from inside the package. Examples include theconventional fresh meat package such as a “PVC stretch wrapped tray” andthe conventional case ready poultry package where a shrink film or bagis hermetically sealed around a tray of meat. In general the fresh meatin a RAP has a higher profile than the tray used to hold the meat sothat the packaging film surrounding the product makes considerablephysical contact with the meat surface.

“Consumer Package” refers to any container in which a meat product isenclosed for the purpose of display and sale to household consumers.

“Case ready” meat refers to a consumer package of fresh meat that isprepackaged and/or labeled at a centralized location and delivered tothe retail market in a format whereby it is ready for immediate displayand sale. The case ready package actively extends the quality life of afresh meat product so as to allow for the extra time that it takes to bepackaged at a centrally located facility, distributed to the retailgrocer and then displayed under lights for consumer selection andpurchase.

As used herein, the phrase “easy open feature” refers to any means foraccessing the contents of a container which obviates the need to cutand/or pierce the container with a knife, scissors or any other sharpimplement. An easy open feature may be in at least one portion of theweb used to form the container and include one or more cuts, notches orsurface-roughened areas, lines of structural weakness or combinationsthereof. Examples of these types of easy open features are described inco-pending U.S. Patent Application Publication Nos. 2005/0084636 toPapenfuss et al. entitled “Tear Initiation and Directional Tear Filmsand Packages Made Therefrom” and 2005/0254731 to Berbert et al. entitled“Easy-Open Handle Bag for Medium to Heavy Duty Applications,” which arehereby incorporated by reference herein. Alternatively, the easy openfeature may include one or more frangible or peelable layers adapted tomanually separate or delaminate at least a portion of the web used toform the container and are described in U.S. Reissued Pat. No. RE37,171to Busche et al., which is hereby incorporated by reference. It will beappreciated that peelable webs may further comprise one or morereclosable peelable layers, examples of which are described in, but notlimited to, co-pending U.S. patent application Ser. No. 11/048,425 toHaedt et al. and Ser. No. 11/247,923 to Cruz et al., which are herebyincorporated by reference herein. Examples of still other alternativeeasy open features include reclosable interlocking fasteners attached toat least a portion of the web used to form the container. Reclosablefasteners, in general, are known and are taught, for example, in U.S.Pat. Nos. 5,063,644; 5,301,394; 5,442,837; 5,964,532; 6,409,384;6,439,770; 6,524,002; 6,527,444; 6,609,827; 6,616,333; 6,632,021;6,663,283; 6,666,580; 6,679,027; and U.S. Patent Application Nos.2002/0097923; and 2002/0196987, each of which is incorporated byreference herein.

EXAMPLES

The following are examples and comparative examples.

Example 1

The following example illustrates the preparation of masterbatch pelletswhich may be used to form a sheet comprising a myoglobin blooming agent.For maximum benefit, sheets comprising a myoglobin blooming agent aregenerally intended to contact the meat product surface, although can beused in other capacities if desired.

A solution of the myoglobin blooming agent is prepared by dissolving asuitable amount of the myoglobin blooming agent in water. Suitableconcentration of myoglobin blooming agent is approximately 0.60 moles ofmyoglobin blooming agent in 60 g of water. The solution is made withwater at room temperature by gently agitating the water/myoglobinblooming agent mixture.

Dow ATTANE® 4201-G VLDPE (obtained from Dow Chemical Company, Midland,Mich.) is loaded into the hopper of a gravimetric dosing unit that ispositioned to feed the polymer into the main feed port of an APVExtrusion Systems MP 2050 50 mm corotating twin screw extruder. Thefeeder is configured to dose the ATTANE at a rate of 41 kg/h. The mixingelements of the twin screw extruder are arranged in a fashion thatallows for feeding and melting of the VLDPE, injection and mixing of thewater/myoglobin blooming agent solution, removal of the water,pressurization of a die and formation of continuous strands of ahomogeneous VLDPE/sodium nitrite blend.

The twin screw extruder is electrically heated so that the feed zone isat 200° F. and the rest of the extruder at 330° F. When the extruderzones achieve the intended temperatures, the drive motor is engaged torotate the extruder screws at about 578 RPM. The ATTANE VLDPE is dosedinto the primary feed port at 41 kg/h. Once a stable, homogeneousextrudate is achieved, the myoglobin blooming agent/water mixture isinjected into the molten VLDPE at injection port. A gear pump operatingat 30 RPM is used to deliver the myoglobin blooming agent/water solutionto the injection port. The injection point is placed in a section of theextruder configured to have high free volume and low pressure. The rateof delivery of the solution is calculated by the time change in mass ofthe water/myoglobin blooming agent mixture. The intended concentrationof 5% is achieved by adjusting the pump speed. A suitable pump speed isabout 33 RPM. The water/myoglobin blooming agent delivery rate ispreferably about 5.4 kg/h.

The mixing elements of the extruder are arranged in a fashion such thatthe liquid water/myoglobin blooming agent solution is prevented frommoving upstream to the primary feed port. Full bore orifice plugs areused to prevent the unwanted upstream migration.

Following injection, the myoglobin blooming agent/water solution rapidlyincreases in temperature. The water fraction of the solution evaporatesand eventually boils. The resultant steam escapes through an atmosphericpressure vent port. Some steam may also escape through the primary feedport. Following this mixing section, the VLDPE/salt blend moves into apressurization section and finally, into an eight hole strand die. Uponexiting the die, the resultant continuous strands are cooled in a waterbath. At the exit of the water bath, an air knife removes some of themoisture clinging to the surface of the stands. After leaving theinfluence of the air knife, the strands are cut into discrete pellets bya rotating knife-style pelletizer. These pellets are subsequently driedin a convection oven at about 50° C., packed in aluminum foil containingbags and stored for use and referred to as masterbatch pellets.

Films for use as the top sheet of a packaging insert are prepared fromthe masterbatch pellets. The loading level of the masterbatch pellets isvaried to produce VLDPE films with an effective myoglobin blooming agentconcentration.

Example 2

The following example illustrates the preparation of an absorbentpackaging insert from a top sheet, absorbent layer and bottom sheet.

A top sheet film is prepared from polyester, polyethylene or other filmcomprising a myoglobin blooming agent, such as provided in Example 1, byco-extrusion, lamination, or coating with a low-melt component, such asa polyethylene or a polypropylene blend. A bottom sheet is selected froma high wet strength paper or non-woven fabric. The absorbent layer iscalendered between the top and bottom sheet. Heat sealing of the top andbottom sheets is accomplished with heated rotary tooling that has beenengraved with a sealing pattern. The gap between the rolls is preciselycontrolled (to within about 0.0005 inches) and effectively seals the topand bottom sheets at commercial production speeds of between about 50fpm and about 500 fpm. Pressure is used to keep the two rolls inposition. Generally, the hydraulic pressure on each end of the upperrolls is set at between about 100 psi and about 2000 psi. The design ofthe sealing pattern, width of the process and materials selected dictatethe pressure required. It will be appreciated by those skilled in theart that the engraving process may be varied to produce packaginginserts with different sealing patterns. For example, the engravingprocess may be designed to produce a packaging insert comprising anexterior seal pattern along one or more edges of the insert.Alternatively, two or more interior seals may be formed across one orboth faces of the insert thereby creating in a quilt-like pattern on oneface of the insert and a goffered structure, respectively. Still othersealing patterns may include both exterior seal patterns along at leastone edge of the insert and interior seal patterns across one or more ofthe faces of the insert.

Example 3

The following example illustrates the preparation of an absorbentpackaging with microperforations from a top sheet, absorbent layer andbottom sheet.

The top sheet is a co-extruded single layer film of HOPE with amyoglobin blooming agent and EVA as the low-melt material. The bottomlayer is a co-extruded single layer film of HOPE and EVA as the low-meltmaterial. The overall thickness of each sheet is about 1.25 mils(thousands of an inch or about 32 microns). The HDPE componentrepresents about 26 microns while the EVA component represents about 6microns. Microperforations in the film are made with hot needleperforation pins in a male/female tooling arrangement. The low-meltsides of the top sheet and bottom sheet are brought together around theabsorbent layer using a set of pattern rolls that are heated to about270° F. The absorbent layer is a conventional Airlaid material ofcellulose fiber/fluff (about 55%), binder fiber (approximately 15%), andsuperabsorbent fiber (about 30%).

Example 4

The following example illustrates the preparation of a punctureresistant insert.

Master batch pellets of polyethylene comprising a myoglobin bloomingagent are prepared according to example 1. A seven layer co-extrudedpuncture resistant film is then prepared. The layers of the film are:nylon/tie/nylon/tie/nylon/tie/PE, wherein the PE layer is formed byblending polyethylene and pellets of a masterbatch comprising themyoglobin blooming agent. The PE sealant layer is the food contact layerof the film. The thickness of the film is typically 6-20 mil, and thefilm is cut into pre-cut sheets, 4″×6″, for example to form the punctureresistant packaging insert. The puncture resistant packaging insert isplaced inside a bag, either a shrink bag or non-shrink bag. The punctureresistant packaging insert can also be formed around a bone or othersharp or rough portion of the food product. The puncture resistantpacking insert can also be formed into a cavity to be placed over a boneor other sharp or rough portion of the food product.

Example 6

The following example illustrates the preparation of a sachet.

Layer 1: PET film adhesively laminated to high opacity filled PE film.

Layer 2: Microporous polypropylene film with Gurley Air permeability of100 sec/100 cc.

Layer 3: Non woven fabric consisting of a mixture of viscose fibers andpolypropylene fibers with a weight of 120 g/m².

The myoglobin blooming agent is placed between layers 1 and 2. A sachetis formed adhering layers 1 and 2 and layers 2 and 3.

The above examples are illustrative only, and should not be interpretedas limiting since further modifications of the disclosed embodimentswill be apparent to those skilled in the art in view of this teaching.All such modifications are deemed to be within the scope of theembodiments disclosed herein.

The invention claimed is:
 1. A packaging insert for a meat productpackage comprising: at least a first thermoplastic layer comprisingpolyethylene and/or ethylene vinyl acetate copolymer and a myoglobinblooming agent that is a nitric oxide donating compound selected fromthe group consisting of inorganic nitrates and inorganic nitrites;wherein the myoglobin blooming agent is present in an amount sufficientto produce a desired red color which does not penetrate to anundesirable depth of the meat product thickness under reduced oxygenconditions; wherein the packaging insert is sized smaller than the meatproduct package to which it is to be inserted and at least a portion ofthe insert is in contact with the meat product.
 2. The packaging insertof claim 1, wherein the myoglobin blooming agent is on at least aportion of a surface of the first layer.
 3. The packaging insert ofclaim 1, wherein the myoglobin blooming agent is incorporated in thefirst layer.
 4. The packaging insert of claim 1, further comprising asecond layer.
 5. The packaging insert of claim 4, wherein the secondlayer comprises an absorbent material and has a meat contact surface. 6.The packaging insert of claim 5, wherein the absorbent materialcomprises a superabsorbent polymer.
 7. The packaging insert of claim 4,wherein the first layer has a meat contact surface.
 8. The packaginginsert of claim 7, wherein the second layer comprises an absorbentmaterial.
 9. The packaging insert of claim 8, wherein the absorbentmaterial comprises a superabsorbent polymer.
 10. The packaging insert ofclaim 8, wherein the first layer is liquid permeable.
 11. The packaginginsert of claim 10, wherein the first layer comprises perforations ormicroperforations.
 12. The packaging insert of claim 8, furthercomprising a third layer wherein the second layer is disposed betweenthe first and third layers, the first layer being attached to the thirdlayer at least partially along opposite marginal edge portions.
 13. Thepackaging insert of claim 12, wherein the third layer comprises apolymeric material, a non-woven material, or a paper material.
 14. Thepackaging insert of claim 12, wherein at least one of the first layer orthird layer is liquid permeable.
 15. The packaging insert of claim 4,wherein the second layer is liquid permeable and has a food contactsurface.
 16. The packaging insert of claim 15, wherein the second layercomprises perforations or microperforations.
 17. The packaging insert ofclaim 15, wherein the first layer comprises an absorbent material. 18.The packaging insert of claim 17, wherein the absorbent materialcomprises a superabsorbent polymer.
 19. The packaging insert of claim 4,further comprising a third layer, wherein the first layer is disposedbetween the second layer and the third layer, the second layer beingattached to the third layer at least partially along marginal edgeportions; and wherein the first layer comprises an absorbent material.20. The packaging insert of claim 19, wherein at least one of the secondlayer or third layer is liquid permeable.
 21. The packaging insert ofclaim 19, wherein at least one of the second layer or third layercomprises a water-soluble resin.